- Email: [email protected]
Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions
Journal Pre-proof Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions J.K. Pine, B. Haugk, S.M. Robinson, A. Darne, C. Wilson, G. Sen, J.J. French, S.A. White, D.M. Manas, R.M. Charnley PII:
S1424-3903(20)30004-1
DOI:
https://doi.org/10.1016/j.pan.2020.01.004
Reference:
PAN 1151
To appear in:
Pancreatology
Received Date: 27 August 2019 Revised Date:
21 December 2019
Accepted Date: 6 January 2020
Please cite this article as: Pine JK, Haugk B, Robinson SM, Darne A, Wilson C, Sen G, French JJ, White SA, Manas DM, Charnley RM, Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions, Pancreatology (2020), doi: https://doi.org/10.1016/j.pan.2020.01.004. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier B.V. on behalf of IAP and EPC.
Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions.
Running title: Resection margins in PDAC
Pine JK1, Haugk B2, Robinson SM1, Darne A2, Wilson C1, Sen G1, French JJ1, White SA1, Manas DM1, Charnley RM1
1
Department of HPB Surgery, Freeman Hospital, Newcastle-upon-Tyne, UK
2
Department of Cellular Pathology, Royal Victoria Infirmary, Newcastle-upon-Tyne, UK
Author to whom correspondence should be addressed:
Mr JK Pine Department of HPB Surgery, Level 4, Freeman Hospital Freeman Road Newcastle-upon-Tyne, UK NE7 7DN Tel No: +447792027361 Email: [email protected] Word count: 3447 Original article. Previously presented at AUGIS annual meeting, Cork, 2017. Acknowledgements: Mr Paul Brown, Leeds Teaching Hospitals – image owner, Figure 1
Abstract
Background: Surgical resection remains the only curative treatment for pancreatic ductal adenocarcinoma (PDAC). The prognostic value of resection margin status following pancreatoduodenectomy (PD) remains controversial. Standardised pathological assessment increases positive margins but limited data is available on the significance of involved margins. We investigated the impact of resection margin status in PDAC on patient outcome. Method: We identified all patients with PD for PDAC at one pancreatic cancer centre between August 2008 and December 2014. Demographic, operative, adjuvant therapeutic and survival data was obtained. Pathology data including resection margin status of specific anatomic margins was collected and analysed. Results: 107 patients were included, all pathologically staged as T3 with 102 N1. 87.9% of patients were R1 of which 53.3% showed direct extension to the resection margin. Median survival for R0 patients versus R1<1mm and R1=0mm was 28.4 versus 15.4 and 25.1 versus 13.4 months. R1=0mm status remained a predictor of poor outcome on multivariate analysis. Evaluation of individual margins (R1<1mm) showed the SMV and SMA margins were associated with poorer overall survival. Multiple involved margins impacted negatively on outcome. SMA margin patient outcome with R1=1-1.9mm was similar to R1=>2mm. Conclusion: Using an R1 definition of <1mm and standardised pathology we demonstrate that R1 rates in PDAC can approach 90%. R1=0mm remained an independent prognostic factor for overall survival. Using R1<1mm we have shown that involvement of medial margins and multiple margins has significant negative impact on overall survival. We conclude that not all margin positivity has the same prognostic significance.
Introduction
Pancreatic ductal adenocarcinoma represents 90% of all primary pancreatic malignancies (1). It is the 10th most common cancer in the UK, accounting for 3% of all cancers, but represents the 5th most common cause of cancer death with a 5 year survival of less than 5% (2). This poor prognosis is partly due to the relatively late presentation seen in this cancer type with the majority of patients being locally advanced or metastatic, and therefore inoperable, at presentation (3). Despite advances in surgical and systemic therapies overall survival remains poor. Surgical resection is the only potentially curative treatment modality. Only 15-20% of patients are operable at presentation and even with these favourable features long-term survival is only 20% with high rates of recurrence (4).
Multiple factors have been shown to influence prognosis following surgical resection. These include tumour size, tumour grade, presence or absence of lymph node metastases, vascular tumor involvement (arterial, portal vein/superior mesenteric vein), perineural tumor growth and resection margin status (5-10).
Determining the exact prognostic significance of resection margin status in PDAC is challenging due to lack of standardisation of its assessment. When properly interpreted it has an important relationship to outcome in pancreatic cancer (11). However, rates of margin positivity (R1) reported in the literature vary markedly from 16% to greater than 75% (12). This wide variability is due to variation in R1 definition and in pathological assessment. There is some evidence that there is no significant difference in outcome between R1=0mm and R1 = <1mm (13-15) whilst other studies have demonstrated prognostically significant stratification according to R1 definition (16). There is still considerable uncertainty what constitutes an adequate margin (>2mm, >5mm etc.) (17). Whereas UICC defines all margins as 0mm, in the UK R1 is currently defined as <1mm for the SMV, SMA, posterior, corpus/neck , bile duct and small intestinal margins and 0mm for the anterior surface (18). Tumour in lymph nodes, adherent to vessel walls and perineural invasion less than 1mm from the margin is also regarded as R1, although conclusive scientific evidence is lacking. PDAC is characterised by highly infiltrative and discontinuous growth making it difficult to assess tumour extent accurately macroscopically and extensive sampling is required to assess margins accurately. Anatomic position of involved margins also appears to be of prognostic significance with several
studies highlighting SMA and SMV as the most commonly involved margins and associating medial margin positivity with poorer outcome (14, 19-21).
On introduction of a standardised protocol involving colour-coded margins, axial slicing, extensive sampling and defining R1 as tumour <1mm from the resection margin (with the exception of the anterior margin), the rate of R1 resection increases considerably and correlates with survival (15). This standardised protocol has been adopted and refined by the Royal College of Pathologists and forms their guidelines for pancreatic cancer assessment in the UK (18).
Since the introduction of standardised pathological assessment of PD specimens (12) ten years ago the relevance of individual resection margins has yet to be assessed prospectively in a UK cohort. We reviewed our experience of PD for PDAC and assess the impact of the various resection margin statuses on patient outcome.
Method
Patient cohort Patients enrolled onto a prospectively maintained database were identified. Of these, 110 patients with a diagnosis of PDAC who underwent a PD, either classic or pylorus preserving, with curative intent undertaken during the period August 2008 to December 2014 were included in the study. All patients were treated at the Freeman Hospital, Newcastle-upon-Tyne, UK. Analysis was limited to histologically confirmed PDAC and other pathologies were excluded. Surgical mortality was defined as death within 30 days of operation and excluded from our analysis.
Data collection
Demographic, operative and adjuvant therapeutic data was obtained from a combination of the HPB departmental database and hospital records. Patient follow-up and survival data was collected from hospital records. Follow-up was defined as the last documented point of contact with the hospital. Survival was calculated using last point of contact (at which point the patient was censored) or date of death in the deceased patients.
Clinical assessment
All patients underwent surgery following discussion in the departmental multi-disciplinary team meeting (MDT). Criteria for resectability included i) absence of distant disease, ii) absence of locally advanced disease and iii) satisfactory patient fitness. Locally advanced disease was defined as involvement of arterial structures or greater than 180o involvement of portal vein/superior mesenteric vein. Involvement of the portal vein/SMV up to 180o was described as borderline resectable. Patients deemed resectable with PV/SMV involvement would be considered for vein resection. No patients who underwent neoadjuvant chemotherapy were included in the study. All patients considered for resection underwent careful pre-operative fitness assessment including cardiopulmonary exercise (CPEX) testing. Surgical resection was standard rather than extended in terms of lymphadenectomy. Regarding dissection around the mesenteric vessels, all tissue was
cleared from the anterior, right side and posterior aspect of the SMV/portal vein as far distally to the first jejunal tributary at least. Tissue was also cleared from the right side of the superior mesenteric artery, including the tissue between the artery and vein. Post-operatively all patients were considered for adjuvant chemotherapy on a case by case basis and referred as appropriate. However, unit policy has been to offer adjuvant chemotherapy as part of the ESPAC pancreatic cancer trials. Follow-up comprised out-patient review (6-monthly for 2 years, annually thereafter). CT imaging was organised when recurrence was suspected. In the event of recurrent disease an oncological opinion was sought regarding palliative therapy.
Pathological assessment
All specimens were assessed by the standardised technique described by Verbeke et al (2008) (12). This pays particular attention to the circumferential margin (CRM) definitions. These are defined as anterior, posterior, SMA and SMV and are illustrated in figure 1. The transection margins consist of the corpus/neck margin, the bile duct margin and proximal and distal gastric/small bowel margins.
Pathological dissection of formalin fixed PDs was performed or closely supervised by specialist pancreatic pathologists. Corpus/neck, anterior, posterior, SMV, SMA margins were painted with an agreed colour code. Following sampling of the transection margins of the pancreatic corpus/neck, common bile duct and duodenum/distal stomach, the pancreatic head was serially and thinly sliced in an axial plane, i.e. perpendicular to the long axis of the duodenum, allowing key anatomical structures (e.g. ampulla, common bile duct, main pancreatic duct) to be seen in the same slices and direct correlation with cross sectional imaging. Macroscopic measurements were taken in accordance with RCPath guidelines (18). Tissue blocks sampled the tumour in relation to anatomical structures relevant to (UICC TNM) T-staging, e.g. duodenum, ampulla, common bile duct or peripancreatic tissue. As it was often difficult to identify the invasive tumour front macroscopically, tumour and the adjacent margins were extensively and systematically sampled (including sampling of all macroscopic visible tumour in most cases). Microscopic assessment and histological report of the specimen was performed as per RCPath guidelines (18). Excision was regarded as incomplete (R1) if tumour was present <1mm from the margin with the exception of the anterior surface where R1=0mm. Individual margins >1mm were measured to a tenth of a millimetre up to at least 5mm. Presence of tumour within lymph nodes, perineural invasion or lymphovascular invasion extending
to within <1mm of the inked margin was documented and regarded as R1. Extension of tumour to the margin (distance 0mm) was also recorded.
Statistical analysis
Data are presented as mean or median (range). Comparisons between the means of normally distributed groups were performed using Student’s T-test. Non-parametric data was analysed using the chi-squared test.
Univariate survival trends were compared using Kaplan-Meier curves and significant differences determined via the log rank test. To determine whether variables were independently linked to prognosis, the Cox proportional hazard model was used. Significant factors on univariate analysis were entered into a multivariate model. A p-value of less than 0.05 was considered significant. All statistical analysis was performed using SPSS version 16 (SPPS Inc., Chicago, Ill., USA).
Results
Three of the 110 patients who underwent PD for PDAC during the defined study period died within 30 days of their operation giving a surgical mortality rate of 2.7%. As these patient deaths were not influenced by resection margin status they have been excluded from the analysis.
Of our remaining cohort of 107 patients 63 were male and 44 female. 59 patients were over the age of 65 years. In regard to pathological assessment all the resected specimens were classified as T3 (22) with five being N0 and the remainder N1. Two PDACs were well differentiated, 37 moderate and 67 demonstrated poor differentiation. One hundred and three patients had evidence of perineural invasion, 103 vascular invasion and 94 lymphatic invasion. Thirty three patients required a PV/SMV resection. Post-operatively 87 patients underwent some form of adjuvant chemotherapy, 16 did not and data was not available for 4 patients. Mean follow-up for our patients was 21.5 months. Mean follow-up for survivors was 29.4 months with 4 patients lost to follow-up inside 12 months. Twoyear survival was 43.7% with a median survival of 18.9 months.
Resection margins – Incidence and predictors of R1
Ninety-four out of 107 pancreatic resections resulted in a pathological R1 outcome (87.9%) using definition of R1 <1mm. In 57 cases tumour was extending to the margin (53.3%). When assessing individual anatomic resection margins the SMV margin was the most commonly involved margin, positive in 70 (65.4%) patients. This was followed by the SMA margin which was positive in 59 (55.1%) and the posterior margin which was positive in 58 (54.2%) patients. The corpus margin was positive in 20 (18.7%) and the anterior surface in 14 (13.1%) patients. The bile duct resection margin was not involved in any specimen (table 1).
We analysed our data to identify factors that were associated with a positive resection margin. The results are shown in table 2. Factors associated with an R1 resection included tumour size (median 32.0mm v 25.5mm, p=0.021) and N stage (2% N0 v 30% N1, p=0.012).
Resection margins – impact on outcome Median survival was significantly shorter in the R1 group (15.4 vs 28.4 months, p=0.004) although on univariate survival analysis it was not a significant factor. However if positive margin was defined as where tumour was reaching the margin (R1=0mm: median survival 13.4 v 25.1 months) a significant impact on overall survival was found on univariate analysis which remained significant on multivariate analysis.
Each resection margin was individually assessed in regard to its impact on patient outcome. SMA margin positivity was associated with poorer survival (HR 2.348 (1.443-3.821), p=0.001) as was the SMV margin (HR 1.809 (1.104-2.963), p=0.019). The two mobilisation margins (anterior and posterior) and the transection margin at the corpus were not found to be statistically significant. These findings are demonstrated in figure 2. When the number of involved margins was examined multiple involved margins had a negative effect on survival (2 margins – HR 2.610 (1.087-6.267), p=0.032, 3 or more margins – HR 2.589 (1.183-5.664), p=0.013) – see table 1.
Resection margins – impact of distance from the margin
We analysed the impact of distance of tumour from margin for both SMA and SMV using 0mm, 0.10.9mm, 1-1.9mm and ≥2mm as groupings. We demonstrated for the SMA margin that distances <1mm were associated with poorer outcome (0mm – HR 5.233 (2.750-9.956) p<0.001, 0.1-0.9mm – HR 1.943 (1.074-3.517) P=0.028) when compared to >2mm group. There was no significant difference in outcome between 1-1.9mm and >2mm distance groupings from the SMA (supplementary table 1). In regard to the SMV margin only a microscopically positive margin of 0mm significantly predicted a poorer outcome (0mm – HR 2.677 (1.375-5.213) p=0.004). The impact of distance of tumour from resection margin on survival is illustrated by the Kaplan-Meier curves in figure 3.
Survival analysis
We also examined other factors that may impact on survival. Our analysis demonstrated that factors associated with reduced overall survival included high tumour grade (HR 2.241 (1.359-3.697), p=0.002), portal vein resection (HR 1.896 (1.172-3.066), p=0.009) and no adjuvant chemotherapy (HR 2.267 (1.249-4.111), p=0.007) – table 3. Multivariate analysis was performed and tumour grade and adjuvant chemotherapy were the only variables that remained significant – table 3.
Discussion
Resection margin status is thought to be an important factor influencing outcome following PD for PDAC but its assessment and R1 rates vary widely in the literature. This results in conflicting evidence regarding its impact on outcome. Using standardised, rigorous pathological assessment (RCPath/Leeds protocol) (15) and an R1 definition of less than 1mm in a prospectively collected cohort of 107 patients undergoing PD for PDAC we have found a R1 rate in excess of 87%. Our study has not shown a significant difference in overall survival comparing the nearly 90% R1 resection to the small minority of R0 resection cases on univariate analysis, but has shown that extension of tumour to the margin (R1=0mm) has a significant impact on overall survival on both univariate and multivariate analysis. When applying R1<1mm it has highlighted that specific anatomic margins (SMA, SMV) and number of margins involved (2 and 3 or more margins) impact directly on survival. We found tumour size and node status to impact on resection margin status and also demonstrated that R1 of less than 1mm from SMA has a significantly worse outcome than a distance of 1-1.9mm on univariate analysis. In addition, tumour grade and adjuvant chemotherapy impacted on survival on multivariate analysis.
Strengths of our study include a relatively large, prospectively collected, single institution cohort of purely stage pT3 (22), chemotherapy naive resected PDAC cases along with the meticulous, systematic pathological assessment performed or supervised by specialist pancreatic pathologists. The latter likely resulted in the very high rate of pT3 and pN1 and allowed consistent resection margin data to be extracted. Limitations of the pathological assessment include the solely macroscopic tumour size assessment and likely poorly reproducible tumour grading. Inherent heterogeneity within the patient cohort and the single institution surgical practice also risks introducing bias. Additionally, over 60% of patients had 2 or more positive margins and a much larger patient cohort would be required to examine the impact on outcome of isolated specific anatomic margin positivity versus specific combinations of positive margins. Similarly, the impact of lymph node metastases, perineural or lymphovascular invasion versus direct tumour infiltration at the margins is well outside the scope of this study.
The plethora of studies examining the role of resection margin status in PDAC following PD over the past two decades have produced clear evidence that the standardised, rigorous pathological
examination of PD by thin axial slicing and extensive sampling according to RCPath/Leeds protocol results in significantly higher R1 rates compared to non-standardised assessment regardless of R1 definition (13-16, 19, 23, 24). Our study contributes further to this growing body of compelling evidence. Using a R1 definition of less than 1mm R1 rates of 80% and higher have been described (15, 16) very similar to the rate observed in our study. Tumour reaching the margin in over 58% of cases in one recent large series (16) is also similar to our findings of 53% although other studies found lower rates of 25% (25). Our higher margin positivity could be related to the inclusion of positive lymph nodes at the margin.
The role of resection margin status on patient outcome is less clearly defined owing to the marked heterogeneity of studies in terms of margin definition and pathological assessment. In addition, the complexity of multiple specific anatomic margins in PD and the sheer number of additional potential negative prognostic factors in PDAC would require prohibitively large case series to accurately determine the role of margin status. Nevertheless, numerous studies have indicated resection margin status to have some impact on outcome. Several studies have shown correlation with overall survival using R1 of less than 1mm (13, 15, 16, 26, 27) and/or using R1 of 0mm (16, 28-31) although some were restricted to univariate analysis and several studies did not use the Leeds/RCPath pathology protocol or alternative meticulous method. Other studies demonstrated impact on outcome only for margin distance cut-offs of 1.5mm or 2.0mm (24, 32). Our finding that direct extension of tumour to the margin (R1=0mm) has a significant impact on overall survival on univariate and multivariate analysis further supports the role of resection margin status as prognostic factor in PDAC following PD. Limited data is available on the role of specific anatomic and multiple margin positivity complicated by historic lack of clear distinction of posterior, SMA and SMV margins and uncertainty about the role of the anterior surface as a margin. Presence of two or more positive margins has been described in 26 to 45% of cases when using the RCPath/Leeds protocol (14, 15, 19, 23). The multiple margin involvement in our study of 60.7% is likely related to the inclusion of lymph node metastases and perineural and lymphovascular invasion at the margin. Several studies have shown impact of R1 status on survival restricted to specific anatomic margins, e.g. posterior (33) or medial margins (14, 21). A positive SMA margin specifically has been found to be a predictor of poor prognosis using non-standardised pathology assessment and R1=0mm (20, 34) but also an independent prognosticator in certain subgroups of post resection PDAC patients when using R1<1mm and RCPath/Leeds protocol (25). This is consistent with our findings.
Two recent detailed and large studies from France and Germany (16, 25) based on rigorous pathological assessment, similar to that used in our study, give a good indication that resection margin status is of prognostic value. Our study also highlights the importance of resection margin status, with R1=0mm at any margin influencing overall survival and R1<1mm at the SMA margin also impacting on outcome. Both Strobel et al (2017) and Delpero et al (2017) also emphasise the urgent need for international agreement to a standardised approach for the pathological assessment of resection margins in PD for PDAC along with the need for detailed measurements of individual anatomic margins. Such a unified approach is pre-requisite to large international collaborative studies with a large enough patient cohort to verify the exact required clearance of each anatomical margin to be of prognostic significance as well as the impact of number of margins involved.
An R0 resection is often thought to be the best opportunity for long term survival in PDAC but it only represents part of the multimodal treatment for these patients. Meticulous surgical technique is vital to ensuring the best possible outcome. A high quality, standard D2 lymphadenectomy ensures accurate pathological staging and can help direct adjuvant therapy (35). Adjuvant therapies form an important part of patient management, with neoadjuvant chemotherapy playing an increasingly prominent role (36). There is evidence that higher R0 resection rates can be achieved following neoadjuvant chemotherapy in borderline resectable tumours (37) and this, along with meticulous surgery, may represent the best hope of achieving longer term survival.
In conclusion, our study emphasises that rigorous pathology assessment of PD for PDAC using RCPath/Leeds protocol can result in a R1<1mm rate approaching 90% and a R1=0mm rate of greater 50%. We have provided further evidence that resection margin status has an impact on outcome and our finding of SMA and SMV margin positivity, as well as multiple margin positivity, having a worse impact on survival suggests that not all margin positivity may be of the same prognostic significance. This highlights the need for accurate measurement of each individual anatomic margin, allowing the prognostic impact of margin positivity to be clearly characterised in large multicentre trials. An R0 resection remains the gold standard in surgery for PD for PDAC. Further work is needed into how this will be achieved, potentially by combining meticulous surgical technique with appropriate neo-adjuvant therapy.
References
1. Hackeng WM, Hruban RH, Offerhaus GJ, Brosens LA. Surgical and molecular pathology of pancreatic neoplasms. Diagn Pathol. 2016;11(1):47. 2. UK CR. Pancreatic cancer statistics 2016 [Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancertype/pancreatic-cancer. 3. Hidalgo M. Pancreatic cancer. N Engl J Med. 2010;362(17):1605-17. 4. Katz MH, Wang H, Fleming JB, Sun CC, Hwang RF, Wolff RA, et al. Long-term survival after multidisciplinary management of resected pancreatic adenocarcinoma. Ann Surg Oncol. 2009;16(4):836-47. 5. Yeo CJ, Cameron JL, Sohn TA, Lillemoe KD, Pitt HA, Talamini MA, et al. Six hundred fifty consecutive pancreaticoduodenectomies in the 1990s: pathology, complications, and outcomes. Ann Surg. 1997;226(3):248-57; discussion 57-60. 6. Pawlik TM, Gleisner AL, Cameron JL, Winter JM, Assumpcao L, Lillemoe KD, et al. Prognostic relevance of lymph node ratio following pancreaticoduodenectomy for pancreatic cancer. Surgery. 2007;141(5):610-8. 7. Fortner JG, Klimstra DS, Senie RT, Maclean BJ. Tumor size is the primary prognosticator for pancreatic cancer after regional pancreatectomy. Ann Surg. 1996;223(2):147-53. 8. Paniccia A, Hosokawa P, Henderson W, Schulick RD, Edil BH, McCarter MD, et al. Characteristics of 10-Year Survivors of Pancreatic Ductal Adenocarcinoma. JAMA Surg. 2015;150(8):701-10. 9. Dusch N, Weiss C, Strobel P, Kienle P, Post S, Niedergethmann M. Factors predicting longterm survival following pancreatic resection for ductal adenocarcinoma of the pancreas: 40 years of experience. J Gastrointest Surg. 2014;18(4):674-81. 10. Ferrone CR, Pieretti-Vanmarcke R, Bloom JP, Zheng H, Szymonifka J, Wargo JA, et al. Pancreatic ductal adenocarcinoma: long-term survival does not equal cure. Surgery. 2012;152(3 Suppl 1):S43-9. 11. Neoptolemos JP, Stocken DD, Dunn JA, Almond J, Beger HG, Pederzoli P, et al. Influence of resection margins on survival for patients with pancreatic cancer treated by adjuvant chemoradiation and/or chemotherapy in the ESPAC-1 randomized controlled trial. Ann Surg. 2001;234(6):758-68. 12. Verbeke CS. Resection margins and R1 rates in pancreatic cancer--are we there yet? Histopathology. 2008;52(7):787-96. 13. Campbell F, Smith RA, Whelan P, Sutton R, Raraty M, Neoptolemos JP, et al. Classification of R1 resections for pancreatic cancer: the prognostic relevance of tumour involvement within 1 mm of a resection margin. Histopathology. 2009;55(3):277-83. 14. Jamieson NB, Foulis AK, Oien KA, Going JJ, Glen P, Dickson EJ, et al. Positive mobilization margins alone do not influence survival following pancreatico-duodenectomy for pancreatic ductal adenocarcinoma. Ann Surg. 2010;251(6):1003-10. 15. Verbeke CS, Leitch D, Menon KV, McMahon MJ, Guillou PJ, Anthoney A. Redefining the R1 resection in pancreatic cancer. Br J Surg. 2006;93(10):1232-7. 16. Strobel O, Hank T, Hinz U, Bergmann F, Schneider L, Springfeld C, et al. Pancreatic Cancer Surgery: The New R-status Counts. Ann Surg. 2017;265(3):565-73. 17. Ethun CG, Kooby DA. The importance of surgical margins in pancreatic cancer. J Surg Oncol. 2016;113(3):283-8.
18. Campbell F, Cairns A, Duthie F, Feakins R. Dataset for the histopathological reporting of carcinomas of the pancreas, ampulla of Vater and common bile duct. In: Pathologists RCo, editor. 2017. 19. Delpero JR, Bachellier P, Regenet N, Le Treut YP, Paye F, Carrere N, et al. Pancreaticoduodenectomy for pancreatic ductal adenocarcinoma: a French multicentre prospective evaluation of resection margins in 150 evaluable specimens. HPB (Oxford). 2014;16(1):20-33. 20. Liu L, Katz MH, Lee SM, Fischer LK, Prakash L, Parker N, et al. Superior Mesenteric Artery Margin of Posttherapy Pancreaticoduodenectomy and Prognosis in Patients With Pancreatic Ductal Adenocarcinoma. Am J Surg Pathol. 2015;39(10):1395-403. 21. Zhang Y, Frampton AE, Cohen P, Kyriakides C, Bong JJ, Habib NA, et al. Tumor infiltration in the medial resection margin predicts survival after pancreaticoduodenectomy for pancreatic ductal adenocarcinoma. J Gastrointest Surg. 2012;16(10):1875-82. 22. Sobin LH, Gospodarowicz MK, Wittekind C, International Union against Cancer. TNM classification of malignant tumours. 7th ed. Chichester: Wiley-Blackwell; 2010. xx, 310 p. p. 23. Esposito I, Kleeff J, Bergmann F, Reiser C, Herpel E, Friess H, et al. Most pancreatic cancer resections are R1 resections. Ann Surg Oncol. 2008;15(6):1651-60. 24. Gebauer F, Tachezy M, Vashist YK, Marx AH, Yekebas E, Izbicki JR, et al. Resection margin clearance in pancreatic cancer after implementation of the Leeds Pathology Protocol (LEEPP): clinically relevant or just academic? World J Surg. 2015;39(2):493-9. 25. Delpero JR, Jeune F, Bachellier P, Regenet N, Le Treut YP, Paye F, et al. Prognostic Value of Resection Margin Involvement After Pancreaticoduodenectomy for Ductal Adenocarcinoma: Updates From a French Prospective Multicenter Study. Ann Surg. 2017;266(5):787-96. 26. Rau BM, Moritz K, Schuschan S, Alsfasser G, Prall F, Klar E. R1 resection in pancreatic cancer has significant impact on long-term outcome in standardized pathology modified for routine use. Surgery. 2012;152(3 Suppl 1):S103-11. 27. Konstantinidis IT, Warshaw AL, Allen JN, Blaszkowsky LS, Castillo CF, Deshpande V, et al. Pancreatic ductal adenocarcinoma: is there a survival difference for R1 resections versus locally advanced unresectable tumors? What is a "true" R0 resection? Ann Surg. 2013;257(4):731-6. 28. Kimbrough CW, St Hill CR, Martin RC, McMasters KM, Scoggins CR. Tumor-positive resection margins reflect an aggressive tumor biology in pancreatic cancer. J Surg Oncol. 2013;107(6):602-7. 29. Mathur A, Ross SB, Luberice K, Kurian T, Vice M, Toomey P, et al. Margin status impacts survival after pancreaticoduodenectomy but negative margins should not be pursued. Am Surg. 2014;80(4):353-60. 30. Janot MS, Kersting S, Belyaev O, Matuschek A, Chromik AM, Suelberg D, et al. Can the new RCP R0/R1 classification predict the clinical outcome in ductal adenocarcinoma of the pancreatic head? Langenbecks Arch Surg. 2012;397(6):917-25. 31. Ghaneh P, Kleeff J, Halloran CM, Raraty M, Jackson R, Melling J, et al. The Impact of Positive Resection Margins on Survival and Recurrence Following Resection and Adjuvant Chemotherapy for Pancreatic Ductal Adenocarcinoma. Ann Surg. 2017. 32. Chang DK, Johns AL, Merrett ND, Gill AJ, Colvin EK, Scarlett CJ, et al. Margin clearance and outcome in resected pancreatic cancer. J Clin Oncol. 2009;27(17):2855-62. 33. Gnerlich JL, Luka SR, Deshpande AD, Dubray BJ, Weir JS, Carpenter DH, et al. Microscopic margins and patterns of treatment failure in resected pancreatic adenocarcinoma. Arch Surg. 2012;147(8):753-60. 34. Kakar S, Shi C, Adsay NV, Fitzgibbons P, Frankel WL, Klimstra DS, et al. Protocol for the Examination of Specimens From Patients With Carcinoma of the Pancreas. In: Pathologists CoA, editor. 2017. 35. Tol JA, Gouma DJ, Bassi C, Dervenis C, Montorsi M, Adham M, et al. Definition of a standard lymphadenectomy in surgery for pancreatic ductal adenocarcinoma: a consensus statement by the International Study Group on Pancreatic Surgery (ISGPS). Surgery. 2014;156(3):591-600.
36. Neoptolemos JP, Kleeff J, Michl P, Costello E, Greenhalf W, Palmer DH. Therapeutic developments in pancreatic cancer: current and future perspectives. Nat Rev Gastroenterol Hepatol. 2018. 37. Ferrone CR, Marchegiani G, Hong TS, Ryan DP, Deshpande V, McDonnell EI, et al. Radiological and surgical implications of neoadjuvant treatment with FOLFIRINOX for locally advanced and borderline resectable pancreatic cancer. Ann Surg. 2015;261(1):12-7.
Tables Table 1 – Analysis of impact of margin involvement on overall survival No of cases
HR
95% CI
p-value*
(%total cases) Multiple
0
13 (12.1%)
-
-
0.029
margins
1
29 (27.1%)
1.365
0.597-3.122
0.461
2
21 (19.6%)
2.610
1.087-6.267
0.032
3+
44 (41.1%)
2.589
1.183-5.664
0.017
Anterior
14 (13.1%)
1.671
0.870-3.209
0.123
Posterior
58 (54.2%)
1.232
0.783-1.939
0.367
SMV
70 (65.4%)
1.809
1.104-2.963
0.019
SMA
59 (55.1%)
2.348
1.443-3.821
0.001
Corpus
20 (18.7%)
1.281
0.725-2.262
0.393
Bile duct
0 (0%)
-
-
-
Transection
R0†
13 (12.1%)
-
-
0.013
v
Mob
13 (12.1%)
0.942
0.341-2.600
0.980
mobilisation
Transect
30 (28.0%)
2.006
0.895-4.497
0.091
Both
51 (47.7%)
2.751
1.262-5.994
0.011
Margins
(HR – hazard ratio, CI – confidence interval, SMV – superior mesenteric vein, SMA – superior mesenteric artery) *Cox regression analysis (univariate) † R0 as defined by tumour present ≥1mm from the margin with the exception of the anterior surface where >0mm
Table 2 – Predictors of R1 resection R1
R0
p-value
94
13
-
Male
58
5
0.110‡
Female
36
8
Median
66.0
67.0
Range
43 - 82
53 – 77
Tumour size
Median
32.0
25.5
(mm)
Range
13 – 65
14 – 48
T stage
2
0
0
3
94
13
0
2
3
1
92
10
Well
2
0
Moderate
32
5
Poor
60
8
Perineural
Yes
92
12
invasion
No
2
1
Lymphatic
Yes
85
9
invasion
No
9
4
Vascular invasion
Yes
91
12
No
3
1
Yes
32
1
No
62
12
Adjuvant
Yes
76
11
chemotherapy
No
15
1
Unknown
3
1
Number of patients Gender
Age (yrs)
N stage
Tumour grade
Vein resection
*Fisher’s exact test †Mann Whitney U test ‡Chi squared test
0.477†
0.021†
-
0.012*
0.785‡
0.325*
0.051*
0.409*
0.061*
0.686*
Table 3 – Factors influencing overall survival (univariate and multivariate analysis) Univariate
Multivariate
Variable
N
HR
CI (95%)
p-value
HR
Overall
107
-
-
-
Male
63
1.071
0.673-
Female
44
≤65
48
>65
59
≤2
9
>2
80
Unknown
18
2
0
3
107
0
5
1
102
Well/Moderate
39
Poor
68
Perineural
Yes
104
invasion
No
3
Lymphatic
Yes
94
invasion
No
13
Vascular
Yes
103
invasion
No
4
Vein resection
Yes
33
No
84
Yes
87
chemotherapy No
16
Gender
Age
Tumour size
T stage
N stage
Tumour grade
Adjuvant
Unknown
4
Margin status
R0
13
(R1<1mm)
R1
94
Margin status
R0
50
(R1=0mm)
R1
57
Cox regression analysis
p-value
-
CI (95%) -
0.774
-
-
-
0.437
-
-
-
0.305
-
-
-
1.704 1.198
0.760-
-
1.890 1.573
0.6623.737
-
-
-
-
-
-
1.144
0.416-
0.795
-
-
-
0.002
1.917
1.1343.240
0.015
0.195
-
-
-
0.599
-
-
-
0.253
-
-
-
0.011
1.098
0.6571.834
0.723
0.007
2.949
1.5845.490
0.001
0.061
-
-
-
<0.001
3.063
1.802-
<0.001
3.145 2.241
1.3593.697
2.606
0.60211.101
1.206
0.6002.423
2.278
0.5569.333
1.860
1.1503.009
2.267
1.2494.111
2.022
0.9684.223
3.418
2.0585.676
5.206
Figures
Figure 1 – Pancreaticoduodenectomy specimen – pathological resection margins (18)
Figure 2 – Kaplan-Meier survival curves for individual resection margins (including numbers at risk)
(a) Anterior margin
Years Positive Negative P=0.119
0 14 93
1 10 69
2 3 32
3 0 14
4 0 7
5 0 4
(b) Posterior margin
Years Positive Negative P=0.565
0 58 49
1 39 40
2 15 20
3 6 8
4 3 5
5 2 2
(c) SMA margin
Years Positive Negative P<0.001
0 59 48
1 40 39
2 11 24
3 2 12
4 1 7
5 0 4
(d) SMV margin
Years Positive Negative P=0.014
0 70 37
1 49 30
2 16 19
3 4 10
4 3 5
5 1 3
(e) Corpus margin
Years Positive Negative P=0.349
0 20 87
1 12 67
2 6 29
3 2 12
4 0 8
5 0 4
Figure 3 – Kaplan-Meier survival curves for distance of tumour from the margin (including numbers at risk)
(a) SMA margin
Years 0mm <1mm 1-1.9mm ≥2mm
P<0.001
0 23 36 11 37
1 11 29 8 31
2 1 10 4 20
3 0 2 0 12
4 0 1 0 7
5 0 0 0 4
(b) SMV margin
Years 0mm <1mm 1-1.9mm ≥2mm
P=0.019
0 26 45 11 25
1 16 33 9 21
2 4 12 4 15
3 1 3 3 7
4 0 3 1 4
5 0 1 1 2
S1424-3903(20)30004-1
DOI:
https://doi.org/10.1016/j.pan.2020.01.004
Reference:
PAN 1151
To appear in:
Pancreatology
Received Date: 27 August 2019 Revised Date:
21 December 2019
Accepted Date: 6 January 2020
Please cite this article as: Pine JK, Haugk B, Robinson SM, Darne A, Wilson C, Sen G, French JJ, White SA, Manas DM, Charnley RM, Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions, Pancreatology (2020), doi: https://doi.org/10.1016/j.pan.2020.01.004. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier B.V. on behalf of IAP and EPC.
Prospective assessment of resection margin status following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma after standardisation of margin definitions.
Running title: Resection margins in PDAC
Pine JK1, Haugk B2, Robinson SM1, Darne A2, Wilson C1, Sen G1, French JJ1, White SA1, Manas DM1, Charnley RM1
1
Department of HPB Surgery, Freeman Hospital, Newcastle-upon-Tyne, UK
2
Department of Cellular Pathology, Royal Victoria Infirmary, Newcastle-upon-Tyne, UK
Author to whom correspondence should be addressed:
Mr JK Pine Department of HPB Surgery, Level 4, Freeman Hospital Freeman Road Newcastle-upon-Tyne, UK NE7 7DN Tel No: +447792027361 Email: [email protected] Word count: 3447 Original article. Previously presented at AUGIS annual meeting, Cork, 2017. Acknowledgements: Mr Paul Brown, Leeds Teaching Hospitals – image owner, Figure 1
Abstract
Background: Surgical resection remains the only curative treatment for pancreatic ductal adenocarcinoma (PDAC). The prognostic value of resection margin status following pancreatoduodenectomy (PD) remains controversial. Standardised pathological assessment increases positive margins but limited data is available on the significance of involved margins. We investigated the impact of resection margin status in PDAC on patient outcome. Method: We identified all patients with PD for PDAC at one pancreatic cancer centre between August 2008 and December 2014. Demographic, operative, adjuvant therapeutic and survival data was obtained. Pathology data including resection margin status of specific anatomic margins was collected and analysed. Results: 107 patients were included, all pathologically staged as T3 with 102 N1. 87.9% of patients were R1 of which 53.3% showed direct extension to the resection margin. Median survival for R0 patients versus R1<1mm and R1=0mm was 28.4 versus 15.4 and 25.1 versus 13.4 months. R1=0mm status remained a predictor of poor outcome on multivariate analysis. Evaluation of individual margins (R1<1mm) showed the SMV and SMA margins were associated with poorer overall survival. Multiple involved margins impacted negatively on outcome. SMA margin patient outcome with R1=1-1.9mm was similar to R1=>2mm. Conclusion: Using an R1 definition of <1mm and standardised pathology we demonstrate that R1 rates in PDAC can approach 90%. R1=0mm remained an independent prognostic factor for overall survival. Using R1<1mm we have shown that involvement of medial margins and multiple margins has significant negative impact on overall survival. We conclude that not all margin positivity has the same prognostic significance.
Introduction
Pancreatic ductal adenocarcinoma represents 90% of all primary pancreatic malignancies (1). It is the 10th most common cancer in the UK, accounting for 3% of all cancers, but represents the 5th most common cause of cancer death with a 5 year survival of less than 5% (2). This poor prognosis is partly due to the relatively late presentation seen in this cancer type with the majority of patients being locally advanced or metastatic, and therefore inoperable, at presentation (3). Despite advances in surgical and systemic therapies overall survival remains poor. Surgical resection is the only potentially curative treatment modality. Only 15-20% of patients are operable at presentation and even with these favourable features long-term survival is only 20% with high rates of recurrence (4).
Multiple factors have been shown to influence prognosis following surgical resection. These include tumour size, tumour grade, presence or absence of lymph node metastases, vascular tumor involvement (arterial, portal vein/superior mesenteric vein), perineural tumor growth and resection margin status (5-10).
Determining the exact prognostic significance of resection margin status in PDAC is challenging due to lack of standardisation of its assessment. When properly interpreted it has an important relationship to outcome in pancreatic cancer (11). However, rates of margin positivity (R1) reported in the literature vary markedly from 16% to greater than 75% (12). This wide variability is due to variation in R1 definition and in pathological assessment. There is some evidence that there is no significant difference in outcome between R1=0mm and R1 = <1mm (13-15) whilst other studies have demonstrated prognostically significant stratification according to R1 definition (16). There is still considerable uncertainty what constitutes an adequate margin (>2mm, >5mm etc.) (17). Whereas UICC defines all margins as 0mm, in the UK R1 is currently defined as <1mm for the SMV, SMA, posterior, corpus/neck , bile duct and small intestinal margins and 0mm for the anterior surface (18). Tumour in lymph nodes, adherent to vessel walls and perineural invasion less than 1mm from the margin is also regarded as R1, although conclusive scientific evidence is lacking. PDAC is characterised by highly infiltrative and discontinuous growth making it difficult to assess tumour extent accurately macroscopically and extensive sampling is required to assess margins accurately. Anatomic position of involved margins also appears to be of prognostic significance with several
studies highlighting SMA and SMV as the most commonly involved margins and associating medial margin positivity with poorer outcome (14, 19-21).
On introduction of a standardised protocol involving colour-coded margins, axial slicing, extensive sampling and defining R1 as tumour <1mm from the resection margin (with the exception of the anterior margin), the rate of R1 resection increases considerably and correlates with survival (15). This standardised protocol has been adopted and refined by the Royal College of Pathologists and forms their guidelines for pancreatic cancer assessment in the UK (18).
Since the introduction of standardised pathological assessment of PD specimens (12) ten years ago the relevance of individual resection margins has yet to be assessed prospectively in a UK cohort. We reviewed our experience of PD for PDAC and assess the impact of the various resection margin statuses on patient outcome.
Method
Patient cohort Patients enrolled onto a prospectively maintained database were identified. Of these, 110 patients with a diagnosis of PDAC who underwent a PD, either classic or pylorus preserving, with curative intent undertaken during the period August 2008 to December 2014 were included in the study. All patients were treated at the Freeman Hospital, Newcastle-upon-Tyne, UK. Analysis was limited to histologically confirmed PDAC and other pathologies were excluded. Surgical mortality was defined as death within 30 days of operation and excluded from our analysis.
Data collection
Demographic, operative and adjuvant therapeutic data was obtained from a combination of the HPB departmental database and hospital records. Patient follow-up and survival data was collected from hospital records. Follow-up was defined as the last documented point of contact with the hospital. Survival was calculated using last point of contact (at which point the patient was censored) or date of death in the deceased patients.
Clinical assessment
All patients underwent surgery following discussion in the departmental multi-disciplinary team meeting (MDT). Criteria for resectability included i) absence of distant disease, ii) absence of locally advanced disease and iii) satisfactory patient fitness. Locally advanced disease was defined as involvement of arterial structures or greater than 180o involvement of portal vein/superior mesenteric vein. Involvement of the portal vein/SMV up to 180o was described as borderline resectable. Patients deemed resectable with PV/SMV involvement would be considered for vein resection. No patients who underwent neoadjuvant chemotherapy were included in the study. All patients considered for resection underwent careful pre-operative fitness assessment including cardiopulmonary exercise (CPEX) testing. Surgical resection was standard rather than extended in terms of lymphadenectomy. Regarding dissection around the mesenteric vessels, all tissue was
cleared from the anterior, right side and posterior aspect of the SMV/portal vein as far distally to the first jejunal tributary at least. Tissue was also cleared from the right side of the superior mesenteric artery, including the tissue between the artery and vein. Post-operatively all patients were considered for adjuvant chemotherapy on a case by case basis and referred as appropriate. However, unit policy has been to offer adjuvant chemotherapy as part of the ESPAC pancreatic cancer trials. Follow-up comprised out-patient review (6-monthly for 2 years, annually thereafter). CT imaging was organised when recurrence was suspected. In the event of recurrent disease an oncological opinion was sought regarding palliative therapy.
Pathological assessment
All specimens were assessed by the standardised technique described by Verbeke et al (2008) (12). This pays particular attention to the circumferential margin (CRM) definitions. These are defined as anterior, posterior, SMA and SMV and are illustrated in figure 1. The transection margins consist of the corpus/neck margin, the bile duct margin and proximal and distal gastric/small bowel margins.
Pathological dissection of formalin fixed PDs was performed or closely supervised by specialist pancreatic pathologists. Corpus/neck, anterior, posterior, SMV, SMA margins were painted with an agreed colour code. Following sampling of the transection margins of the pancreatic corpus/neck, common bile duct and duodenum/distal stomach, the pancreatic head was serially and thinly sliced in an axial plane, i.e. perpendicular to the long axis of the duodenum, allowing key anatomical structures (e.g. ampulla, common bile duct, main pancreatic duct) to be seen in the same slices and direct correlation with cross sectional imaging. Macroscopic measurements were taken in accordance with RCPath guidelines (18). Tissue blocks sampled the tumour in relation to anatomical structures relevant to (UICC TNM) T-staging, e.g. duodenum, ampulla, common bile duct or peripancreatic tissue. As it was often difficult to identify the invasive tumour front macroscopically, tumour and the adjacent margins were extensively and systematically sampled (including sampling of all macroscopic visible tumour in most cases). Microscopic assessment and histological report of the specimen was performed as per RCPath guidelines (18). Excision was regarded as incomplete (R1) if tumour was present <1mm from the margin with the exception of the anterior surface where R1=0mm. Individual margins >1mm were measured to a tenth of a millimetre up to at least 5mm. Presence of tumour within lymph nodes, perineural invasion or lymphovascular invasion extending
to within <1mm of the inked margin was documented and regarded as R1. Extension of tumour to the margin (distance 0mm) was also recorded.
Statistical analysis
Data are presented as mean or median (range). Comparisons between the means of normally distributed groups were performed using Student’s T-test. Non-parametric data was analysed using the chi-squared test.
Univariate survival trends were compared using Kaplan-Meier curves and significant differences determined via the log rank test. To determine whether variables were independently linked to prognosis, the Cox proportional hazard model was used. Significant factors on univariate analysis were entered into a multivariate model. A p-value of less than 0.05 was considered significant. All statistical analysis was performed using SPSS version 16 (SPPS Inc., Chicago, Ill., USA).
Results
Three of the 110 patients who underwent PD for PDAC during the defined study period died within 30 days of their operation giving a surgical mortality rate of 2.7%. As these patient deaths were not influenced by resection margin status they have been excluded from the analysis.
Of our remaining cohort of 107 patients 63 were male and 44 female. 59 patients were over the age of 65 years. In regard to pathological assessment all the resected specimens were classified as T3 (22) with five being N0 and the remainder N1. Two PDACs were well differentiated, 37 moderate and 67 demonstrated poor differentiation. One hundred and three patients had evidence of perineural invasion, 103 vascular invasion and 94 lymphatic invasion. Thirty three patients required a PV/SMV resection. Post-operatively 87 patients underwent some form of adjuvant chemotherapy, 16 did not and data was not available for 4 patients. Mean follow-up for our patients was 21.5 months. Mean follow-up for survivors was 29.4 months with 4 patients lost to follow-up inside 12 months. Twoyear survival was 43.7% with a median survival of 18.9 months.
Resection margins – Incidence and predictors of R1
Ninety-four out of 107 pancreatic resections resulted in a pathological R1 outcome (87.9%) using definition of R1 <1mm. In 57 cases tumour was extending to the margin (53.3%). When assessing individual anatomic resection margins the SMV margin was the most commonly involved margin, positive in 70 (65.4%) patients. This was followed by the SMA margin which was positive in 59 (55.1%) and the posterior margin which was positive in 58 (54.2%) patients. The corpus margin was positive in 20 (18.7%) and the anterior surface in 14 (13.1%) patients. The bile duct resection margin was not involved in any specimen (table 1).
We analysed our data to identify factors that were associated with a positive resection margin. The results are shown in table 2. Factors associated with an R1 resection included tumour size (median 32.0mm v 25.5mm, p=0.021) and N stage (2% N0 v 30% N1, p=0.012).
Resection margins – impact on outcome Median survival was significantly shorter in the R1 group (15.4 vs 28.4 months, p=0.004) although on univariate survival analysis it was not a significant factor. However if positive margin was defined as where tumour was reaching the margin (R1=0mm: median survival 13.4 v 25.1 months) a significant impact on overall survival was found on univariate analysis which remained significant on multivariate analysis.
Each resection margin was individually assessed in regard to its impact on patient outcome. SMA margin positivity was associated with poorer survival (HR 2.348 (1.443-3.821), p=0.001) as was the SMV margin (HR 1.809 (1.104-2.963), p=0.019). The two mobilisation margins (anterior and posterior) and the transection margin at the corpus were not found to be statistically significant. These findings are demonstrated in figure 2. When the number of involved margins was examined multiple involved margins had a negative effect on survival (2 margins – HR 2.610 (1.087-6.267), p=0.032, 3 or more margins – HR 2.589 (1.183-5.664), p=0.013) – see table 1.
Resection margins – impact of distance from the margin
We analysed the impact of distance of tumour from margin for both SMA and SMV using 0mm, 0.10.9mm, 1-1.9mm and ≥2mm as groupings. We demonstrated for the SMA margin that distances <1mm were associated with poorer outcome (0mm – HR 5.233 (2.750-9.956) p<0.001, 0.1-0.9mm – HR 1.943 (1.074-3.517) P=0.028) when compared to >2mm group. There was no significant difference in outcome between 1-1.9mm and >2mm distance groupings from the SMA (supplementary table 1). In regard to the SMV margin only a microscopically positive margin of 0mm significantly predicted a poorer outcome (0mm – HR 2.677 (1.375-5.213) p=0.004). The impact of distance of tumour from resection margin on survival is illustrated by the Kaplan-Meier curves in figure 3.
Survival analysis
We also examined other factors that may impact on survival. Our analysis demonstrated that factors associated with reduced overall survival included high tumour grade (HR 2.241 (1.359-3.697), p=0.002), portal vein resection (HR 1.896 (1.172-3.066), p=0.009) and no adjuvant chemotherapy (HR 2.267 (1.249-4.111), p=0.007) – table 3. Multivariate analysis was performed and tumour grade and adjuvant chemotherapy were the only variables that remained significant – table 3.
Discussion
Resection margin status is thought to be an important factor influencing outcome following PD for PDAC but its assessment and R1 rates vary widely in the literature. This results in conflicting evidence regarding its impact on outcome. Using standardised, rigorous pathological assessment (RCPath/Leeds protocol) (15) and an R1 definition of less than 1mm in a prospectively collected cohort of 107 patients undergoing PD for PDAC we have found a R1 rate in excess of 87%. Our study has not shown a significant difference in overall survival comparing the nearly 90% R1 resection to the small minority of R0 resection cases on univariate analysis, but has shown that extension of tumour to the margin (R1=0mm) has a significant impact on overall survival on both univariate and multivariate analysis. When applying R1<1mm it has highlighted that specific anatomic margins (SMA, SMV) and number of margins involved (2 and 3 or more margins) impact directly on survival. We found tumour size and node status to impact on resection margin status and also demonstrated that R1 of less than 1mm from SMA has a significantly worse outcome than a distance of 1-1.9mm on univariate analysis. In addition, tumour grade and adjuvant chemotherapy impacted on survival on multivariate analysis.
Strengths of our study include a relatively large, prospectively collected, single institution cohort of purely stage pT3 (22), chemotherapy naive resected PDAC cases along with the meticulous, systematic pathological assessment performed or supervised by specialist pancreatic pathologists. The latter likely resulted in the very high rate of pT3 and pN1 and allowed consistent resection margin data to be extracted. Limitations of the pathological assessment include the solely macroscopic tumour size assessment and likely poorly reproducible tumour grading. Inherent heterogeneity within the patient cohort and the single institution surgical practice also risks introducing bias. Additionally, over 60% of patients had 2 or more positive margins and a much larger patient cohort would be required to examine the impact on outcome of isolated specific anatomic margin positivity versus specific combinations of positive margins. Similarly, the impact of lymph node metastases, perineural or lymphovascular invasion versus direct tumour infiltration at the margins is well outside the scope of this study.
The plethora of studies examining the role of resection margin status in PDAC following PD over the past two decades have produced clear evidence that the standardised, rigorous pathological
examination of PD by thin axial slicing and extensive sampling according to RCPath/Leeds protocol results in significantly higher R1 rates compared to non-standardised assessment regardless of R1 definition (13-16, 19, 23, 24). Our study contributes further to this growing body of compelling evidence. Using a R1 definition of less than 1mm R1 rates of 80% and higher have been described (15, 16) very similar to the rate observed in our study. Tumour reaching the margin in over 58% of cases in one recent large series (16) is also similar to our findings of 53% although other studies found lower rates of 25% (25). Our higher margin positivity could be related to the inclusion of positive lymph nodes at the margin.
The role of resection margin status on patient outcome is less clearly defined owing to the marked heterogeneity of studies in terms of margin definition and pathological assessment. In addition, the complexity of multiple specific anatomic margins in PD and the sheer number of additional potential negative prognostic factors in PDAC would require prohibitively large case series to accurately determine the role of margin status. Nevertheless, numerous studies have indicated resection margin status to have some impact on outcome. Several studies have shown correlation with overall survival using R1 of less than 1mm (13, 15, 16, 26, 27) and/or using R1 of 0mm (16, 28-31) although some were restricted to univariate analysis and several studies did not use the Leeds/RCPath pathology protocol or alternative meticulous method. Other studies demonstrated impact on outcome only for margin distance cut-offs of 1.5mm or 2.0mm (24, 32). Our finding that direct extension of tumour to the margin (R1=0mm) has a significant impact on overall survival on univariate and multivariate analysis further supports the role of resection margin status as prognostic factor in PDAC following PD. Limited data is available on the role of specific anatomic and multiple margin positivity complicated by historic lack of clear distinction of posterior, SMA and SMV margins and uncertainty about the role of the anterior surface as a margin. Presence of two or more positive margins has been described in 26 to 45% of cases when using the RCPath/Leeds protocol (14, 15, 19, 23). The multiple margin involvement in our study of 60.7% is likely related to the inclusion of lymph node metastases and perineural and lymphovascular invasion at the margin. Several studies have shown impact of R1 status on survival restricted to specific anatomic margins, e.g. posterior (33) or medial margins (14, 21). A positive SMA margin specifically has been found to be a predictor of poor prognosis using non-standardised pathology assessment and R1=0mm (20, 34) but also an independent prognosticator in certain subgroups of post resection PDAC patients when using R1<1mm and RCPath/Leeds protocol (25). This is consistent with our findings.
Two recent detailed and large studies from France and Germany (16, 25) based on rigorous pathological assessment, similar to that used in our study, give a good indication that resection margin status is of prognostic value. Our study also highlights the importance of resection margin status, with R1=0mm at any margin influencing overall survival and R1<1mm at the SMA margin also impacting on outcome. Both Strobel et al (2017) and Delpero et al (2017) also emphasise the urgent need for international agreement to a standardised approach for the pathological assessment of resection margins in PD for PDAC along with the need for detailed measurements of individual anatomic margins. Such a unified approach is pre-requisite to large international collaborative studies with a large enough patient cohort to verify the exact required clearance of each anatomical margin to be of prognostic significance as well as the impact of number of margins involved.
An R0 resection is often thought to be the best opportunity for long term survival in PDAC but it only represents part of the multimodal treatment for these patients. Meticulous surgical technique is vital to ensuring the best possible outcome. A high quality, standard D2 lymphadenectomy ensures accurate pathological staging and can help direct adjuvant therapy (35). Adjuvant therapies form an important part of patient management, with neoadjuvant chemotherapy playing an increasingly prominent role (36). There is evidence that higher R0 resection rates can be achieved following neoadjuvant chemotherapy in borderline resectable tumours (37) and this, along with meticulous surgery, may represent the best hope of achieving longer term survival.
In conclusion, our study emphasises that rigorous pathology assessment of PD for PDAC using RCPath/Leeds protocol can result in a R1<1mm rate approaching 90% and a R1=0mm rate of greater 50%. We have provided further evidence that resection margin status has an impact on outcome and our finding of SMA and SMV margin positivity, as well as multiple margin positivity, having a worse impact on survival suggests that not all margin positivity may be of the same prognostic significance. This highlights the need for accurate measurement of each individual anatomic margin, allowing the prognostic impact of margin positivity to be clearly characterised in large multicentre trials. An R0 resection remains the gold standard in surgery for PD for PDAC. Further work is needed into how this will be achieved, potentially by combining meticulous surgical technique with appropriate neo-adjuvant therapy.
References
1. Hackeng WM, Hruban RH, Offerhaus GJ, Brosens LA. Surgical and molecular pathology of pancreatic neoplasms. Diagn Pathol. 2016;11(1):47. 2. UK CR. Pancreatic cancer statistics 2016 [Available from: http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancertype/pancreatic-cancer. 3. Hidalgo M. Pancreatic cancer. N Engl J Med. 2010;362(17):1605-17. 4. Katz MH, Wang H, Fleming JB, Sun CC, Hwang RF, Wolff RA, et al. Long-term survival after multidisciplinary management of resected pancreatic adenocarcinoma. Ann Surg Oncol. 2009;16(4):836-47. 5. Yeo CJ, Cameron JL, Sohn TA, Lillemoe KD, Pitt HA, Talamini MA, et al. Six hundred fifty consecutive pancreaticoduodenectomies in the 1990s: pathology, complications, and outcomes. Ann Surg. 1997;226(3):248-57; discussion 57-60. 6. Pawlik TM, Gleisner AL, Cameron JL, Winter JM, Assumpcao L, Lillemoe KD, et al. Prognostic relevance of lymph node ratio following pancreaticoduodenectomy for pancreatic cancer. Surgery. 2007;141(5):610-8. 7. Fortner JG, Klimstra DS, Senie RT, Maclean BJ. Tumor size is the primary prognosticator for pancreatic cancer after regional pancreatectomy. Ann Surg. 1996;223(2):147-53. 8. Paniccia A, Hosokawa P, Henderson W, Schulick RD, Edil BH, McCarter MD, et al. Characteristics of 10-Year Survivors of Pancreatic Ductal Adenocarcinoma. JAMA Surg. 2015;150(8):701-10. 9. Dusch N, Weiss C, Strobel P, Kienle P, Post S, Niedergethmann M. Factors predicting longterm survival following pancreatic resection for ductal adenocarcinoma of the pancreas: 40 years of experience. J Gastrointest Surg. 2014;18(4):674-81. 10. Ferrone CR, Pieretti-Vanmarcke R, Bloom JP, Zheng H, Szymonifka J, Wargo JA, et al. Pancreatic ductal adenocarcinoma: long-term survival does not equal cure. Surgery. 2012;152(3 Suppl 1):S43-9. 11. Neoptolemos JP, Stocken DD, Dunn JA, Almond J, Beger HG, Pederzoli P, et al. Influence of resection margins on survival for patients with pancreatic cancer treated by adjuvant chemoradiation and/or chemotherapy in the ESPAC-1 randomized controlled trial. Ann Surg. 2001;234(6):758-68. 12. Verbeke CS. Resection margins and R1 rates in pancreatic cancer--are we there yet? Histopathology. 2008;52(7):787-96. 13. Campbell F, Smith RA, Whelan P, Sutton R, Raraty M, Neoptolemos JP, et al. Classification of R1 resections for pancreatic cancer: the prognostic relevance of tumour involvement within 1 mm of a resection margin. Histopathology. 2009;55(3):277-83. 14. Jamieson NB, Foulis AK, Oien KA, Going JJ, Glen P, Dickson EJ, et al. Positive mobilization margins alone do not influence survival following pancreatico-duodenectomy for pancreatic ductal adenocarcinoma. Ann Surg. 2010;251(6):1003-10. 15. Verbeke CS, Leitch D, Menon KV, McMahon MJ, Guillou PJ, Anthoney A. Redefining the R1 resection in pancreatic cancer. Br J Surg. 2006;93(10):1232-7. 16. Strobel O, Hank T, Hinz U, Bergmann F, Schneider L, Springfeld C, et al. Pancreatic Cancer Surgery: The New R-status Counts. Ann Surg. 2017;265(3):565-73. 17. Ethun CG, Kooby DA. The importance of surgical margins in pancreatic cancer. J Surg Oncol. 2016;113(3):283-8.
18. Campbell F, Cairns A, Duthie F, Feakins R. Dataset for the histopathological reporting of carcinomas of the pancreas, ampulla of Vater and common bile duct. In: Pathologists RCo, editor. 2017. 19. Delpero JR, Bachellier P, Regenet N, Le Treut YP, Paye F, Carrere N, et al. Pancreaticoduodenectomy for pancreatic ductal adenocarcinoma: a French multicentre prospective evaluation of resection margins in 150 evaluable specimens. HPB (Oxford). 2014;16(1):20-33. 20. Liu L, Katz MH, Lee SM, Fischer LK, Prakash L, Parker N, et al. Superior Mesenteric Artery Margin of Posttherapy Pancreaticoduodenectomy and Prognosis in Patients With Pancreatic Ductal Adenocarcinoma. Am J Surg Pathol. 2015;39(10):1395-403. 21. Zhang Y, Frampton AE, Cohen P, Kyriakides C, Bong JJ, Habib NA, et al. Tumor infiltration in the medial resection margin predicts survival after pancreaticoduodenectomy for pancreatic ductal adenocarcinoma. J Gastrointest Surg. 2012;16(10):1875-82. 22. Sobin LH, Gospodarowicz MK, Wittekind C, International Union against Cancer. TNM classification of malignant tumours. 7th ed. Chichester: Wiley-Blackwell; 2010. xx, 310 p. p. 23. Esposito I, Kleeff J, Bergmann F, Reiser C, Herpel E, Friess H, et al. Most pancreatic cancer resections are R1 resections. Ann Surg Oncol. 2008;15(6):1651-60. 24. Gebauer F, Tachezy M, Vashist YK, Marx AH, Yekebas E, Izbicki JR, et al. Resection margin clearance in pancreatic cancer after implementation of the Leeds Pathology Protocol (LEEPP): clinically relevant or just academic? World J Surg. 2015;39(2):493-9. 25. Delpero JR, Jeune F, Bachellier P, Regenet N, Le Treut YP, Paye F, et al. Prognostic Value of Resection Margin Involvement After Pancreaticoduodenectomy for Ductal Adenocarcinoma: Updates From a French Prospective Multicenter Study. Ann Surg. 2017;266(5):787-96. 26. Rau BM, Moritz K, Schuschan S, Alsfasser G, Prall F, Klar E. R1 resection in pancreatic cancer has significant impact on long-term outcome in standardized pathology modified for routine use. Surgery. 2012;152(3 Suppl 1):S103-11. 27. Konstantinidis IT, Warshaw AL, Allen JN, Blaszkowsky LS, Castillo CF, Deshpande V, et al. Pancreatic ductal adenocarcinoma: is there a survival difference for R1 resections versus locally advanced unresectable tumors? What is a "true" R0 resection? Ann Surg. 2013;257(4):731-6. 28. Kimbrough CW, St Hill CR, Martin RC, McMasters KM, Scoggins CR. Tumor-positive resection margins reflect an aggressive tumor biology in pancreatic cancer. J Surg Oncol. 2013;107(6):602-7. 29. Mathur A, Ross SB, Luberice K, Kurian T, Vice M, Toomey P, et al. Margin status impacts survival after pancreaticoduodenectomy but negative margins should not be pursued. Am Surg. 2014;80(4):353-60. 30. Janot MS, Kersting S, Belyaev O, Matuschek A, Chromik AM, Suelberg D, et al. Can the new RCP R0/R1 classification predict the clinical outcome in ductal adenocarcinoma of the pancreatic head? Langenbecks Arch Surg. 2012;397(6):917-25. 31. Ghaneh P, Kleeff J, Halloran CM, Raraty M, Jackson R, Melling J, et al. The Impact of Positive Resection Margins on Survival and Recurrence Following Resection and Adjuvant Chemotherapy for Pancreatic Ductal Adenocarcinoma. Ann Surg. 2017. 32. Chang DK, Johns AL, Merrett ND, Gill AJ, Colvin EK, Scarlett CJ, et al. Margin clearance and outcome in resected pancreatic cancer. J Clin Oncol. 2009;27(17):2855-62. 33. Gnerlich JL, Luka SR, Deshpande AD, Dubray BJ, Weir JS, Carpenter DH, et al. Microscopic margins and patterns of treatment failure in resected pancreatic adenocarcinoma. Arch Surg. 2012;147(8):753-60. 34. Kakar S, Shi C, Adsay NV, Fitzgibbons P, Frankel WL, Klimstra DS, et al. Protocol for the Examination of Specimens From Patients With Carcinoma of the Pancreas. In: Pathologists CoA, editor. 2017. 35. Tol JA, Gouma DJ, Bassi C, Dervenis C, Montorsi M, Adham M, et al. Definition of a standard lymphadenectomy in surgery for pancreatic ductal adenocarcinoma: a consensus statement by the International Study Group on Pancreatic Surgery (ISGPS). Surgery. 2014;156(3):591-600.
36. Neoptolemos JP, Kleeff J, Michl P, Costello E, Greenhalf W, Palmer DH. Therapeutic developments in pancreatic cancer: current and future perspectives. Nat Rev Gastroenterol Hepatol. 2018. 37. Ferrone CR, Marchegiani G, Hong TS, Ryan DP, Deshpande V, McDonnell EI, et al. Radiological and surgical implications of neoadjuvant treatment with FOLFIRINOX for locally advanced and borderline resectable pancreatic cancer. Ann Surg. 2015;261(1):12-7.
Tables Table 1 – Analysis of impact of margin involvement on overall survival No of cases
HR
95% CI
p-value*
(%total cases) Multiple
0
13 (12.1%)
-
-
0.029
margins
1
29 (27.1%)
1.365
0.597-3.122
0.461
2
21 (19.6%)
2.610
1.087-6.267
0.032
3+
44 (41.1%)
2.589
1.183-5.664
0.017
Anterior
14 (13.1%)
1.671
0.870-3.209
0.123
Posterior
58 (54.2%)
1.232
0.783-1.939
0.367
SMV
70 (65.4%)
1.809
1.104-2.963
0.019
SMA
59 (55.1%)
2.348
1.443-3.821
0.001
Corpus
20 (18.7%)
1.281
0.725-2.262
0.393
Bile duct
0 (0%)
-
-
-
Transection
R0†
13 (12.1%)
-
-
0.013
v
Mob
13 (12.1%)
0.942
0.341-2.600
0.980
mobilisation
Transect
30 (28.0%)
2.006
0.895-4.497
0.091
Both
51 (47.7%)
2.751
1.262-5.994
0.011
Margins
(HR – hazard ratio, CI – confidence interval, SMV – superior mesenteric vein, SMA – superior mesenteric artery) *Cox regression analysis (univariate) † R0 as defined by tumour present ≥1mm from the margin with the exception of the anterior surface where >0mm
Table 2 – Predictors of R1 resection R1
R0
p-value
94
13
-
Male
58
5
0.110‡
Female
36
8
Median
66.0
67.0
Range
43 - 82
53 – 77
Tumour size
Median
32.0
25.5
(mm)
Range
13 – 65
14 – 48
T stage
2
0
0
3
94
13
0
2
3
1
92
10
Well
2
0
Moderate
32
5
Poor
60
8
Perineural
Yes
92
12
invasion
No
2
1
Lymphatic
Yes
85
9
invasion
No
9
4
Vascular invasion
Yes
91
12
No
3
1
Yes
32
1
No
62
12
Adjuvant
Yes
76
11
chemotherapy
No
15
1
Unknown
3
1
Number of patients Gender
Age (yrs)
N stage
Tumour grade
Vein resection
*Fisher’s exact test †Mann Whitney U test ‡Chi squared test
0.477†
0.021†
-
0.012*
0.785‡
0.325*
0.051*
0.409*
0.061*
0.686*
Table 3 – Factors influencing overall survival (univariate and multivariate analysis) Univariate
Multivariate
Variable
N
HR
CI (95%)
p-value
HR
Overall
107
-
-
-
Male
63
1.071
0.673-
Female
44
≤65
48
>65
59
≤2
9
>2
80
Unknown
18
2
0
3
107
0
5
1
102
Well/Moderate
39
Poor
68
Perineural
Yes
104
invasion
No
3
Lymphatic
Yes
94
invasion
No
13
Vascular
Yes
103
invasion
No
4
Vein resection
Yes
33
No
84
Yes
87
chemotherapy No
16
Gender
Age
Tumour size
T stage
N stage
Tumour grade
Adjuvant
Unknown
4
Margin status
R0
13
(R1<1mm)
R1
94
Margin status
R0
50
(R1=0mm)
R1
57
Cox regression analysis
p-value
-
CI (95%) -
0.774
-
-
-
0.437
-
-
-
0.305
-
-
-
1.704 1.198
0.760-
-
1.890 1.573
0.6623.737
-
-
-
-
-
-
1.144
0.416-
0.795
-
-
-
0.002
1.917
1.1343.240
0.015
0.195
-
-
-
0.599
-
-
-
0.253
-
-
-
0.011
1.098
0.6571.834
0.723
0.007
2.949
1.5845.490
0.001
0.061
-
-
-
<0.001
3.063
1.802-
<0.001
3.145 2.241
1.3593.697
2.606
0.60211.101
1.206
0.6002.423
2.278
0.5569.333
1.860
1.1503.009
2.267
1.2494.111
2.022
0.9684.223
3.418
2.0585.676
5.206
Figures
Figure 1 – Pancreaticoduodenectomy specimen – pathological resection margins (18)
Figure 2 – Kaplan-Meier survival curves for individual resection margins (including numbers at risk)
(a) Anterior margin
Years Positive Negative P=0.119
0 14 93
1 10 69
2 3 32
3 0 14
4 0 7
5 0 4
(b) Posterior margin
Years Positive Negative P=0.565
0 58 49
1 39 40
2 15 20
3 6 8
4 3 5
5 2 2
(c) SMA margin
Years Positive Negative P<0.001
0 59 48
1 40 39
2 11 24
3 2 12
4 1 7
5 0 4
(d) SMV margin
Years Positive Negative P=0.014
0 70 37
1 49 30
2 16 19
3 4 10
4 3 5
5 1 3
(e) Corpus margin
Years Positive Negative P=0.349
0 20 87
1 12 67
2 6 29
3 2 12
4 0 8
5 0 4
Figure 3 – Kaplan-Meier survival curves for distance of tumour from the margin (including numbers at risk)
(a) SMA margin
Years 0mm <1mm 1-1.9mm ≥2mm
P<0.001
0 23 36 11 37
1 11 29 8 31
2 1 10 4 20
3 0 2 0 12
4 0 1 0 7
5 0 0 0 4
(b) SMV margin
Years 0mm <1mm 1-1.9mm ≥2mm
P=0.019
0 26 45 11 25
1 16 33 9 21
2 4 12 4 15
3 1 3 3 7
4 0 3 1 4
5 0 1 1 2