- Email: [email protected]
Preoperative Submucosal Injection of Carbon Nanoparticles Improves Lymph Node Staging Accuracy in Rectal Cancer after Neoadjuvant Chemoradiotherapy
Preoperative Submucosal Injection of Carbon Nanoparticles Improves Lymph Node Staging Accuracy in Rectal Cancer after Neoadjuvant Chemoradiotherapy Yanan Wang, MD, Haijun Deng, MD, Hongyuan Chen, Jun Yan, MD, PhD, Guoxin Li, MD, PhD
MD,
Hao Liu,
MD, PhD,
Qi Xue,
MD,
The aim of this study was to evaluate the association between the number of nodes harvested and the rate of node positivity, and to evaluate the effect of carbon nanoparticles (CNPs) in improving lymph node detection and staging accuracy in patients who received neoadjuvant chemoradiotherapy (NCRT) followed by curative resection. STUDY DESIGN: Between September 2008 and June 2014, 152 consecutive rectal cancer patients treated with NCRT and curative resection were included. Forty-five patients underwent preoperative submucosal injection of CNPs (CNP group); the other patients underwent surgery only (control group). The relationship between the number of lymph nodes harvested and the rate of node positivity was investigated. A comparison of the number of harvested lymph nodes and the node positivity rate between the 2 groups was also performed. The lymph nodes in the CNP group were analyzed in detail. RESULTS: The rate of node positivity increased gradually from 8.6% in patients with 1 to 5 nodes assessed to 37.8% in patients with 17 to 44 nodes assessed. The number of lymph nodes harvested was an independent risk factor for node positivity (p ¼ 0.036). The mean number of lymph nodes retrieved in the CNP group was more than in the control group (21.1 vs 8.0, p ¼ 0.000). The percentage of patients with positive lymph nodes was lower than in the control group (19.6% vs 35.6%, p ¼ 0.037). In the CNP group, of 58 metastatic lymph nodes, 45 (77.6%) were dyed. Of 37 metastatic lymph nodes smaller than 5 mm, 33 (89.2%) were dyed. CONCLUSIONS: More precise oncologic prognosis assessment was provided for patients with rectal cancer after NCRT by increasing the number of lymph nodes counted using a dye-tracing method, indicating that the use of CNPs is beneficial. (J Am Coll Surg 2015;-:1e8. 2015 by the American College of Surgeons)
BACKGROUND:
Valid pathologic assessment of lymph node involvement is a crucial component of staging because it provides the most relevant indication of prognosis and is a determinant of further treatment strategies for patients with colorectal cancer. To achieve appropriate node staging, current guidelines recommend that at least 12 to 14 lymph nodes should be obtained from a colorectal cancer specimen,1,2 with certain studies suggesting that obtaining even more nodes may be beneficial.3 Neoadjuvant chemoradiotherapy (NCRT) followed by total mesorectal excision is the current standard of treatment for patients with locally advanced rectal cancer, improving local tumor control and allowing sphincter-preserving surgery.4 However, recent reports have identified a significant decrease in the number of lymph nodes detected in surgical specimens
CME questions for this article available at http://jacscme.facs.org Disclosure Information: Authors have nothing to disclose. Timothy J Eberlein, Editor-in-Chief, has nothing to disclose. Support: This study was supported by the Major Program of Science and Technology Program of Guangzhou (No. 201300000087), the Research Fund of Public Welfare in Health Industry of the National Health and Family Planning Commission of China (No. 201402015 and No. 201502039), the National Key Technology R&D Program (No. 2013BAI05B05), and the Key Clinical Specialty Discipline Construction Program. Drs Wang and Deng contributed equally to this work. Received April 5, 2015; Revised May 27, 2015; Accepted July 9, 2015. From the Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China. Correspondence address: Guoxin Li, MD, PhD, Department of General Surgery, Nanfang Hospital, Southern Medical University, 1838 North, Guangzhou Ave, Guangzhou 510-515, China. email: [email protected]
ª 2015 by the American College of Surgeons Published by Elsevier Inc.
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Abbreviations and Acronyms
APR CNPs LAR NCRT OS
¼ ¼ ¼ ¼ ¼
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abdominoperineal resection carbon nanoparticles low anterior resection neoadjuvant chemoradiotherapy overall survival
from patients with rectal cancer after NCRT.5-7 Although the influence of this reduction in lymph node detection on node staging accuracy is still controversial,4 certain studies have shown a significantly higher number of nodes harvested from node-positive patients compared with node-negative patients.8 Accurate positive nodal status was recently shown to be associated with prognosis9 and to help to guide adjuvant chemotherapy in patients with rectal cancer after NCRT.10,11 Therefore, improving lymph node detection is beneficial to patient outcomes. In a previous study, we found that submucosal carbon nanoparticle (CNP) staining can improve lymph node retrieval from gastrointestinal carcinoma specimens, without additional operative or pathologic time requirements.12 To further investigate the relationship between the number of nodes retrieved and the rate of node positivity, and to evaluate the effect of submucosal CNP staining on improvements in lymph node detection and staging accuracy, we have used this technique since August 2013 in patients who have received NCRT followed by curative resection.
METHODS Patients Drawing from a prospectively maintained institutional colorectal cancer database13 at Nanfang Hospital, Southern Medical University, we identified152 consecutive patients with adenocarcinomas located in the middle or distal rectum that were staged as cT3-4N0M0 or TanyN1-2M0 by MRI or transrectal ultrasonography, who were treated with NCRT and curative resection between September 2008 and June 2014. Preoperative submucosal CNP staining was introduced gradually, starting in August 2013 with a group of 45 patients, referred to as the CNP group. The other 107 patients did not receive CNPs and constituted the control group. Written consent was provided by all of the participating patients, and the Ethics Committee of Nanfang Hospital, Southern Medical University approved the study. Neoadjuvant chemoradiotherapy and surgery Standardized NCRT consisted of external beam radiation with a cumulative dose of 50.4 Gy in 25 fractions. Concurrent chemotherapy was administered either as 5-FU
monotherapy (oral capecitabine) or as a combined regime of 5-FU/oxaliplatin. The patients underwent either a low anterior resection (LAR) or an abdominoperineal resection (APR) after completion of NCRT. Two experienced colorectal surgeons performed the procedures according to total mesorectal excision principles, and the height of the inferior mesenteric artery was taken into account. No extended lateral lymph node dissections were performed. If necessary, extra-anatomic resections and ileostomies were performed. The median interval between neoadjuvant chemotherapy and surgery was 7.3 weeks (range 4 to 13 weeks). Carbon nanoparticle injection In the CNP group, 0.5 mL of CNP suspension (0.5 mL: 25 mg, Chongqing LUMMY Pharmaceutical Co) was injected into the submucosal layer using a rectal speculum at 3 points around the primary tumor 1 day before surgery. Pathologic examination All lymph nodes were manually harvested from fresh specimens before formalin fixation by the same assistant, who had participated in a study of lymph node yields in colorectal cancer and who was accustomed to finding as many lymph nodes as possible. Standard pathologic tumor staging of the specimens was performed by dedicated gastrointestinal cancer pathologists via routine hematoxylin-eosin staining for identification of involved lymph nodes according to the guidelines of the College of American Pathologists.14 Statistical analysis Data are presented as mean ( SD) for continuous variables and as frequency (%) for categorical variables. Differences between groups were compared by the Mann-Whitney U test for continuous variables and the chi-square test or Fisher’s exact test for categorical variables. Univariate and multivariate logistic regression models were used to evaluate the association between the number of lymph nodes harvested and the rate of node positivity. A p value < 0.05 was considered significant. All statistical analyses were performed with SPSS for Windows (version 17.0, SPSS Inc).
RESULTS Patient characteristics A total of 152 patients were included in the analysis. The mean age of the subjects was 53.7 years (range 32 to 78 years), and 113 (74.3%) patients were men. Ninety-one (59.9%) patients underwent LAR, and 61 (40.1%) patients had APR. A laparoscopic technique was used in
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Clinicopathologic Characteristics of the Two Groups of Patients
Characteristic
Sex Male Female Age, y, mean SD Neoadjuvant treatment 5-FU monotherapy 5-FU/oxaliplatin Tumor site, cm <6 612 Tumor size, cm* <2.5 2.5 Type of operation LAR APR Pre-treatment stagey II III Postoperative stagey 0 I II III Postoperative T stagey T0 T1 T2 T3 T4 Tumor differentiation Well to moderate Poorz Lymph nodes, n, mean SD
Total (n ¼ 152)
Carbon nanoparticle group (n ¼ 45)
Control group (n ¼ 107)
p Value
113 (74.3) 39 (25.7) 53.7 11.7
34 (75.6) 11 (24.4) 53.1 12.0
79 (73.8) 28 (26.2) 54.0 11.6
0.824
60 (39.5) 92 (60.5)
18 (40) 27 (60)
42 (39.3) 65 (60.7)
79 (52.0) 73 (48.0)
23 (51.1) 22 (48.9)
56 (52.3) 51 (47.7)
77 (50.7) 75 (49.3)
18 (40.0) 27 (60.0)
59 (55.1) 48 (44.9)
91 (59.9) 61 (40.1)
29 (64.4) 16 (35.6)
62 (57.9) 45 (42.1)
53 (34.9) 99 (65.1)
14 (31.1) 31 (68.9)
39 (36.4) 68 (63.6)
16 51 48 37
(10.5) (33.6) (31.6) (24.3)
8 9 12 16
(17.8) (20) (26.6) (35.6)
8 42 36 21
(7.5) (39.3) (33.6) (19.6)
16 28 32 72 4
(10.5) (18.4) (21.1) (47.4) (2.6)
8 6 6 24 1
(17.8) (13.3) (13.3) (53.3) (2.2)
8 22 26 48 3
(7.5) (20.6) (24.3) (44.9) (2.8)
0.674 0.931
0.890
0.088
0.455
0.528
0.014
0.124
0.422 121 (79.6) 31 (20.4) 11.9 8.8
34 (75.6) 11 (24.4) 21.1 9.6
87 (81.3) 20 (18.7) 8.0 4.6
0.000
Data presented as n (%) unless otherwise indicated. *Largest tumor diameter. y T and N stages according to the American Joint Committee on Cancer 7th ed. z Including mucinous, signet-ring cell carcinoma. APR, abdominoperineal resection; LAR, low anterior resection.
147 (97%) cases. After NCRT, downstaging was observed in 27 (60%) patients in the CNP group and 80 (74.8%) patients in the control group (p ¼ 0.014). The mean number of lymph nodes harvested in all patients was 11.9 (range 1 to 44), and pathologic tumor staging identified 37 (24.3%) patients with lymph node metastases. The patients’ clinicopathologic characteristics are shown in Table 1.
Relationship between the number of nodes harvested and the node positivity rate The numbers of lymph nodes harvested were categorized into 4 groups (1 to 5, 6 to 8, 9 to 16, and 17 to 44) according to the interquartile range for each patient. The rate of node positivity increased gradually, from 8.6% in patients with 1 to 5 nodes harvested to 37.8% in patients with 17 to 44 nodes harvested. The positive correlation between the
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Figure 1. Relationship between the number of lymph nodes harvested and the node positivity rate.
number of nodes and node positivity was monotonic, with no plateau (Fig. 1). To evaluate the relationship between the number of lymph nodes harvested and node positivity, univariate and multivariate logistic regression analyses were performed. As shown in Table 2, the number of lymph nodes harvested was found to be an independent risk factor for the rate of node positivity (p ¼ 0.113) after adjusting Table 2.
for several confounding variables, including T stage and tumor differentiation. Effect of carbon nanoparticle staining on lymph node detection As shown in Table 3, for the CNP group, the mean time for lymph node retrieval was shorter than that in the
Univariate and Multivariate Analyses of Factors Influencing Lymph Node Metastases in This Cohort
Factors
Sex (male/female) Age, y (>65 vs 65) Site, cm (6 vs <6) Surgery (APR vs LAR) Tumor size, cm* (2.5 vs <2.5) Postoperative T stagey (yp T3-4 vs yp T0-2) Neoadjuvant treatment (5-FU/oxaliplatin vs 5-FU monotherapy) Interval, wk <6 6e8 >8 Tumor differentiation (poorz, vs well to moderate) Lymph node retrieval 1e5 6e8 9e16 17e44
Univariate analysis Odds ratio p Value
1.10 0.26 0.78 1.37 2.32
(0.48e2.54) (0.06e1.15) (0.37e1.64) (0.65e2.90) (1.07e5.00)
4.34 (1.88e10.03) 0.94 (0.44e2.02) 1 0.67 (0.29e1.51) 0.29 (0.09e0.92) 9.06 (3.76e21.83) 1 1.94 (0.45e8.42) 5.53 (1.44e21.29) 6.49 (1.67e25.23)
0.827 0.075 0.504 0.408 0.032 0.001 0.879 0.104 d 0.329 0.036 0.000 0.012 d 0.377 0.013 0.007
*Greatest tumor diameter. y T and N stages according to the American Joint Committee on Cancer 7th ed. z Including mucinous, signet-ring cell carcinoma. APR, abdominoperineal resection; LAR, low anterior resection; yp, pathologic stage after neoadjuvant chemoradiation.
Multivariate analysis Odds ratio p Value
1.56 (0.63e3.91)
0.339
3.34 (1.30e8.63)
0.012
8.98 (3.25e24.80)
0.000 0.036 d 0.113 0.008 0.009
1 3.82 (0.73e20.08) 8.07 (1.72e37.87) 8.02 (1.68e38.31)
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Lymph Node Dissections in the Two Groups Carbon nanoparticle group
Variable
Time required for LN retrieval, min, mean SD LN count, mean SD Patients, n (%) LN <12 LN 12 LN status N0 Nþ
Control group
p Value
27.6 3.5 34.6 4.3 0.000 21.1 9.6 8.0 4.6 0.000 5 (11.1) 40 (88.9)
84 (78.5) 23 (21.5)
0.000 0.037
29 (64.4) 16 (35.6)
86 (80.4) 21 (19.6)
LN, lymph node.
control group (27.6 vs 34.6 minutes, p ¼ 0.000). A comparison of the number of lymph nodes detected between the control and the CNP groups is presented in Table 3. The mean number of lymph nodes retrieved differed markedly, ranging from 21.1 in the CNP group to 8.0 in the control group (p ¼ 0.000). Furthermore, the percentage of patients with a minimum of 12 lymph nodes was 88.9% in the CNP group, which was significantly higher than the rate of 21.5% in the control group (p ¼ 0.000). Additionally, the node positivity rate was 35.6% (16 of 45) in the CNP group, which was higher than the 19.6% (21 of 107) node positivity rate in the control group (p ¼ 0.037). In the CNP group, all patients were successfully traced with CNPs (Fig. 2), and there were no reports of acute or chronic systemic toxicity. The rates of dyed nodes were 84.8% (806 of 951) for all lymph nodes and 87.5% (538 of 615) for lymph nodes smaller than 5 mm. Among the 58 metastatic lymph nodes, 45 (77.6%) were dyed, and of the 37 metastatic lymph nodes smaller than 5 mm, 33 (89.2%) were dyed (Table 4).
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DISCUSSION Accurate evaluation of a patient’s node status is important because lymph node involvement has been widely reported as one of the strongest determinants of survival in patients with rectal cancer treated with NCRT.15,16 Reliable nodal staging of rectal cancer requires detection and evaluation of a certain number of nodes.17 However, as reported in previous studies, NCRT significantly reduces the number of lymph nodes harvested, with fewer than 12 nodes detected per specimen on average.17,18 Because of the National Comprehensive Cancer Network (NCCN) recommendation that all patients receiving adjuvant chemotherapy complete 6 months of treatment, including NCRT, regardless of downstaging after neoadjuvant treatment and surgery,19 there has been little interest in studying the association between the number of nodes harvested and the rate of node positivity. In recent years, however, an increasing number of studies have shown that adjuvant chemotherapy after surgery is not beneficial for patients with pathologic complete responses or yp stage I/II.10,11,20,21 These results indicate the importance of evaluating the association between the number of nodes harvested and the rate of node positivity after NCRT to improve the accuracy of nodal staging. In this study, the numbers of lymph nodes harvested were categorized into 4 intervals (1 to 5, 6 to 8, 9 to 16, and 17 to 44) according to the interquartile range of each patient. The rate of node positivity increased gradually, with corresponding increases in the number of harvested lymph nodes. This result is in agreement with reports by Kim and colleagues8 and Persiani and associates.22 However, because of the limited number of patients in our study, we were unable to obtain a sufficient number of harvested lymph nodes to reach a stable rate of node positivity. Nevertheless, the univariate and multivariate logistic regression analyses showed that
Figure 2. (A) Specimen and the dyed lymph nodes (arrows) and (B) harvested lymph nodes.
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Table 4. Detection of Lymph Nodes and Metastatic Lymph Nodes in the Carbon Nanoparticle Group
Variable
Stained metastatic LNs n %
Overall, n
Stained LNs n %
Metastatic LNs, n
951 45
806 84.8 45 100
58 16
45 16
77.6 100
336 615
268 538
21 37
12 33
57.1 89.2
Overall LNs Patients LN size, mm 5 <5
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79.8 87.5
LN, lymph node.
the number of lymph nodes harvested was an independent risk factor for node positivity and that N stage should be underestimated because of omission of positive lymph nodes in patients from whom fewer lymph nodes are harvested. This result may explain the finding of nodenegative patients with 6 or fewer harvested lymph nodes who had significantly poorer disease-free survival (DFS) and overall survival (OS) in La Torre and coworkers’ study.23 Because it is necessary to harvest more lymph nodes to attain accurate N staging, suitable postoperative chemotherapy recommendations, and a precise oncologic prognosis, it is important to find a simple and effective method to obtain more lymph nodes from a specimen after NCRT and to enhance the rate of node positivity. The fat clearance technique has been reported to improve lymph node harvesting and the accuracy of staging,24 but it is not suitable for daily practice due to the additional laboratory procedures, time required, and its potential hazards. Alternatively, in Okada and coauthors’ study,25 preoperative tracing using India ink was shown to increase the number of retrieved lymph nodes in patients after NCRT (14 vs 8, p < 0.01). Carbon nanoparticles are another widely used lymph node tracer in patients with thyroid and gastrointestinal
cancers, and this tracer has better lymphotropic effects and a slower metabolic velocity than ink.12,26 In a previous study, we found that submucosal CNP staining could improve lymph node retrieval from gastrointestinal carcinomas without additional operative or pathologic time requirements.12 In this study, we also discovered that more lymph nodes were harvested more rapidly when submucosal CNP staining was used. In particular, beginning in August 2013, preoperative submucosal CNP staining was used in 45 patients. For these 45 patients, the mean number of harvested nodes was 21.1, which was significantly greater than the per-patient mean of 8.0 lymph modes harvested in patients who were not administered CNPs (p ¼ 0.002). Meanwhile, the mean time spent on lymph node retrieval was 27.6 minutes in the CNP group, which was significantly less than that in the control group (34.6 minutes). Due to the increase in the number of lymph nodes harvested, 35.6% of cases were identified as yp stage III in the CNP group, which was significantly higher than the rate in the control group (19.6% of cases; p ¼ 0.037). In this study, pre-treatment staging and NCRT protocols were consistent between the CNP and the control groups, but we discovered less downstaging in the CNP group, which might have been due to underestimation of the lymph node metastasis rate in the control group. Therefore, the application of CNPs might favor more accurate postoperative N staging, and a more appropriate decision about postoperative chemotherapy could be made accordingly, which would eventually help us to predict patient prognoses more precisely. It has been suggested that a decrease in the size of lymph nodes (<5 mm) caused by lymphocyte destruction or atrophy of the stroma due to NCRT is the main reason for the reduced number of lymph nodes harvested from specimens processed by conventional manual retrieval.27 Through analysis of lymph nodes from patients in the CNP group, approximately 64.7% (615 of 951) of lymph
Figure 3. Rectum with (A) an accurately dyed layer and (B) with an excessively dyed layer.
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node diameters were found to be <5 mm, and these were difficult to identify using visual-tactile methods. This result demonstrates that after NCRT, most lymph nodes do not disappear, but are instead reduced in size.28 These lymph nodes are more difficult to detect but are still present.29 As a good tracer of lymph nodes, CNPs were able to dye approximately 84.8% (806 of 951) of lymph nodes in the present study. Among nodes with diameters <5 mm, 87.5% (538 of 615) were dyed, suggesting that CNPs play an important role in the detection of small nodes that can be overlooked during conventional manual detection. We found that 6.0% (37 of 615) of these small lymph nodes were metastatic. Of these small metastatic lymph nodes, approximately 89.2% (33 of 37) were stained by CNPs. This finding may account for the higher node positivity rate in the CNP group than in the control group. To sufficiently stain the lymph nodes, we used a long needle to conduct a peri-tumor, 3-point submucosal injection of CNPs through a rectal speculum 1 day before surgery. Because the inferior tumor margin could be observed through the rectal speculum in mid-low rectal cancer patients, the injection method was easily conducted in the ward without further endoscopy, which is both beneficial to patients and welcomed by surgeons. The key aspect of this method lies in the accurate injection of CNPs into the submucosal layer, rather than into the mesorectum or the pararectal space. Otherwise, the identification of pararectal lymph nodes (6 patients) and the intraoperative identification of fascias and spaces (4 patients) would be negatively affected (Fig. 3). We injected saline into the submucosa to expand the layer and to facilitate subsequent CNP injection. Our study has certain limitations. First, we began to use CNPs for lymph node staining and collection in August 2013; therefore, we had to use retrospective data from the colorectal cancer database13 at Nanfang Hospital that were obtained before this point. Second, because only a moderate number of patients were included in this study, the optimal number of lymph nodes required to stage patients with locally advanced rectal cancer treated with NCRT is unclear. Therefore, a large-scale prospective study is necessary to further confirm these results.
CONCLUSIONS In conclusion, more accurate N staging and more precise oncologic prognosis assessment were achieved for patients with rectal cancer following NCRT by increasing the number of lymph nodes counted using a dye-tracing method, indicating that the use of CNPs is beneficial.
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Author Contributions Study conception and design: Wang, Li Acquisition of data: Deng, Chen Analysis and interpretation of data: Liu, Xue Drafting of the manuscript: Wang, Li Critical revision: Yan, Li REFERENCES 1. Edge SB, Compton CC. The American Joint Committee on Cancer: the 7th edition of the AJCC cancer staging manual and the future of TNM. Ann Surg Oncol 2010;17: 1471e1474. 2. Nelson H, Petrelli N, Carlin A, et al. Guidelines 2000 for colon and rectal cancer surgery. J Natl Cancer Inst 2001;93: 583e596. 3. Washington MK, Berlin J, Branton PA, et al. Protocol for the examination of specimens from patients with primary carcinomas of the colon and rectum. Arch Pathol Lab Med 2008;132:1182e1193. 4. Kapiteijn E, Marijnen CA, Nagtegaal ID, et al. Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer. N Engl J Med 2001;345:638e646. 5. Ha YH, Jeong SY, Lim SB, et al. Influence of preoperative chemoradiotherapy on the number of lymph nodes retrieved in rectal cancer. Ann Surg 2010;252:336e340. 6. Morcos B, Baker B, Al Masri M, et al. Lymph node yield in rectal cancer surgery: effect of preoperative chemoradiotherapy. Eur J Surg Oncol 2010;36:345e349. 7. Baxter NN, Morris AM, Rothenberger DA, Tepper JE. Impact of preoperative radiation for rectal cancer on subsequent lymph node evaluation: a population-based analysis. Int J Radiat Oncol Biol Phys 2005;61:426e431. 8. Kim NK, Baik SH, Seong JS, et al. Oncologic outcomes after neoadjuvant chemoradiation followed by curative resection with tumor-specific mesorectal excision for fixed locally advanced rectal cancer: Impact of postirradiated pathologic downstaging on local recurrence and survival. Ann Surg 2006;244:1024e1030. 9. Ishihara S, Watanabe T, Kiyomatsu T, et al. Prognostic significance of response to preoperative radiotherapy, lymph node metastasis, and CEA level in patients undergoing total mesorectal excision of rectal cancer. Int J Colorectal Dis 2010;25: 1417e1425. 10. Haynes AB, You YN, Hu CY, et al. Postoperative chemotherapy use after neoadjuvant chemoradiotherapy for rectal cancer: Analysis of Surveillance, Epidemiology, and End Results-Medicare data, 1998-2007. Cancer 2014;120: 1162e1170. 11. Geva R, Itzkovich E, Shamai S, et al. Is there a role for adjuvant chemotherapy in pathological complete response rectal cancer tumors following neoadjuvant chemoradiotherapy? J Cancer Res Clin Oncol 2014;140:1489e1494. 12. Chen H, Wang Y, Xue F, et al. [Application of subserosal injection of carbon nanoparticles via infusion needle to label lymph nodes in laparoscopic radical gastrectomy]. Zhonghua wei chang wai ke za zhi (Chinese J Gastrointest Surg) 2014; 17:457e460. 13. Liang YZ, Yu J, Zhang C, et al. [Construction and application of evaluation system of laparoscopic colorectal surgery based
8
14.
15.
16.
17.
18. 19. 20. 21.
Wang et al
Carbon Nanoparticles in Rectal Cancer
on clinical data mining]. Zhonghua wei chang wai ke za zhi (Chinese J Gastrointest Surg) 2010;13:741e744. Washington MK, Berlin J, Branton P, et al. Protocol for the examination of specimens from patients with primary carcinoma of the colon and rectum. Arch Pathol Lab Med 2009; 133:1539e1551. Leibold T, Shia J, Ruo L, et al. Prognostic implications of the distribution of lymph node metastases in rectal cancer after neoadjuvant chemoradiotherapy. J Clin Oncol 2008;26: 2106e2111. Chang GJ, Rodriguez-Bigas MA, Eng C, Skibber JM. Lymph node status after neoadjuvant radiotherapy for rectal cancer is a biologic predictor of outcome. Cancer 2009;115: 5432e5440. Rullier A, Laurent C, Capdepont M, et al. Lymph nodes after preoperative chemoradiotherapy for rectal carcinoma: number, status, and impact on survival. Am J Surg Pathol 2008;32: 45e50. Scott N, Thorne C, Jayne D. Lymph node retrieval after neoadjuvant radiotherapy for rectal adenocarcinoma. J Clin Pathol 2004;57:335e336. Rectal cancer, NCCN guidelines. Available at: http://www. nccn.org/professionals/physician_gls/pdf/rectal.pdf version 3. Accessed September 2, 2015. Gao P, Song YX, Sun JX, et al. Which is the best postoperative chemotherapy regimen in patients with rectal cancer after neoadjuvant therapy? BMC Cancer 2014;14:888. Sainato A, Cernusco Luna Nunzia V, Valentini V, et al. No benefit of adjuvant Fluorouracil Leucovorin chemotherapy after neoadjuvant chemoradiotherapy in locally advanced cancer of the rectum (LARC): Long term results of a randomized trial (I-CNR-RT). Radiother Oncol 2014;113:223e229.
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22. Persiani R, Biondi A, Gambacorta MA, et al. Prognostic implications of the lymph node count after neoadjuvant treatment for rectal cancer. Br J Surg 2014;101:133e142. 23. La Torre M, Mazzuca F, Ferri M, et al. The importance of lymph node retrieval and lymph node ratio following preoperative chemoradiation of rectal cancer. Colorectal Dis 2013;15: e382ee388. 24. Gehoff A, Basten O, Sprenger T, et al. Optimal lymph node harvest in rectal cancer (UICC stages II and III) after preoperative 5-FU-based radiochemotherapy. Acetone compression is a new and highly efficient method. Am J Surg Pathol 2012;36: 202e213. 25. Okada K, Sadahiro S, Suzuki T, Tanaka A, Saito G, Kamijo A. Use of preoperative tattooing to increase lymph nodes (LNs) retrieved in patients with locally advanced rectal cancer who receive preoperative chemoradiotherapy (CRT): A randomized controlled trial. J Clin Oncol 2014;32:561. 26. Shen H, Wei B, Feng S, Zhou Q. [Efficiency of carbon nanoparticles in level VI lymphadenectomy for thyroid carcinoma and prevention of postoperative hypoparathyroidism]. Zhonghua er bi yan hou tou jing wai ke za zhi (Chinese J Otorhinolaryngol Head Neck Surg) 2014;49:817e820. 27. Shvero J, Koren R, Marshak G, et al. Histological changes in the cervical lymph nodes after radiotherapy. Oncol Rep 2001; 8:909e911. 28. Kim JS, Sohn DK, Park JW, et al. Prognostic significance of distribution of lymph node metastasis in advanced mid or low rectal cancer. J Surg Oncol 2011;104:486e492. 29. Farinella E, Vigano L, Fava MC, et al. In vivo lymph node mapping and pattern of metastasis spread in locally advanced mid/low rectal cancer after neoadjuvant chemoradiotherapy. Int J Colorectal Dis 2013;28:1523e1529.
MD,
Hao Liu,
MD, PhD,
Qi Xue,
MD,
The aim of this study was to evaluate the association between the number of nodes harvested and the rate of node positivity, and to evaluate the effect of carbon nanoparticles (CNPs) in improving lymph node detection and staging accuracy in patients who received neoadjuvant chemoradiotherapy (NCRT) followed by curative resection. STUDY DESIGN: Between September 2008 and June 2014, 152 consecutive rectal cancer patients treated with NCRT and curative resection were included. Forty-five patients underwent preoperative submucosal injection of CNPs (CNP group); the other patients underwent surgery only (control group). The relationship between the number of lymph nodes harvested and the rate of node positivity was investigated. A comparison of the number of harvested lymph nodes and the node positivity rate between the 2 groups was also performed. The lymph nodes in the CNP group were analyzed in detail. RESULTS: The rate of node positivity increased gradually from 8.6% in patients with 1 to 5 nodes assessed to 37.8% in patients with 17 to 44 nodes assessed. The number of lymph nodes harvested was an independent risk factor for node positivity (p ¼ 0.036). The mean number of lymph nodes retrieved in the CNP group was more than in the control group (21.1 vs 8.0, p ¼ 0.000). The percentage of patients with positive lymph nodes was lower than in the control group (19.6% vs 35.6%, p ¼ 0.037). In the CNP group, of 58 metastatic lymph nodes, 45 (77.6%) were dyed. Of 37 metastatic lymph nodes smaller than 5 mm, 33 (89.2%) were dyed. CONCLUSIONS: More precise oncologic prognosis assessment was provided for patients with rectal cancer after NCRT by increasing the number of lymph nodes counted using a dye-tracing method, indicating that the use of CNPs is beneficial. (J Am Coll Surg 2015;-:1e8. 2015 by the American College of Surgeons)
BACKGROUND:
Valid pathologic assessment of lymph node involvement is a crucial component of staging because it provides the most relevant indication of prognosis and is a determinant of further treatment strategies for patients with colorectal cancer. To achieve appropriate node staging, current guidelines recommend that at least 12 to 14 lymph nodes should be obtained from a colorectal cancer specimen,1,2 with certain studies suggesting that obtaining even more nodes may be beneficial.3 Neoadjuvant chemoradiotherapy (NCRT) followed by total mesorectal excision is the current standard of treatment for patients with locally advanced rectal cancer, improving local tumor control and allowing sphincter-preserving surgery.4 However, recent reports have identified a significant decrease in the number of lymph nodes detected in surgical specimens
CME questions for this article available at http://jacscme.facs.org Disclosure Information: Authors have nothing to disclose. Timothy J Eberlein, Editor-in-Chief, has nothing to disclose. Support: This study was supported by the Major Program of Science and Technology Program of Guangzhou (No. 201300000087), the Research Fund of Public Welfare in Health Industry of the National Health and Family Planning Commission of China (No. 201402015 and No. 201502039), the National Key Technology R&D Program (No. 2013BAI05B05), and the Key Clinical Specialty Discipline Construction Program. Drs Wang and Deng contributed equally to this work. Received April 5, 2015; Revised May 27, 2015; Accepted July 9, 2015. From the Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China. Correspondence address: Guoxin Li, MD, PhD, Department of General Surgery, Nanfang Hospital, Southern Medical University, 1838 North, Guangzhou Ave, Guangzhou 510-515, China. email: [email protected]
ª 2015 by the American College of Surgeons Published by Elsevier Inc.
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Abbreviations and Acronyms
APR CNPs LAR NCRT OS
¼ ¼ ¼ ¼ ¼
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abdominoperineal resection carbon nanoparticles low anterior resection neoadjuvant chemoradiotherapy overall survival
from patients with rectal cancer after NCRT.5-7 Although the influence of this reduction in lymph node detection on node staging accuracy is still controversial,4 certain studies have shown a significantly higher number of nodes harvested from node-positive patients compared with node-negative patients.8 Accurate positive nodal status was recently shown to be associated with prognosis9 and to help to guide adjuvant chemotherapy in patients with rectal cancer after NCRT.10,11 Therefore, improving lymph node detection is beneficial to patient outcomes. In a previous study, we found that submucosal carbon nanoparticle (CNP) staining can improve lymph node retrieval from gastrointestinal carcinoma specimens, without additional operative or pathologic time requirements.12 To further investigate the relationship between the number of nodes retrieved and the rate of node positivity, and to evaluate the effect of submucosal CNP staining on improvements in lymph node detection and staging accuracy, we have used this technique since August 2013 in patients who have received NCRT followed by curative resection.
METHODS Patients Drawing from a prospectively maintained institutional colorectal cancer database13 at Nanfang Hospital, Southern Medical University, we identified152 consecutive patients with adenocarcinomas located in the middle or distal rectum that were staged as cT3-4N0M0 or TanyN1-2M0 by MRI or transrectal ultrasonography, who were treated with NCRT and curative resection between September 2008 and June 2014. Preoperative submucosal CNP staining was introduced gradually, starting in August 2013 with a group of 45 patients, referred to as the CNP group. The other 107 patients did not receive CNPs and constituted the control group. Written consent was provided by all of the participating patients, and the Ethics Committee of Nanfang Hospital, Southern Medical University approved the study. Neoadjuvant chemoradiotherapy and surgery Standardized NCRT consisted of external beam radiation with a cumulative dose of 50.4 Gy in 25 fractions. Concurrent chemotherapy was administered either as 5-FU
monotherapy (oral capecitabine) or as a combined regime of 5-FU/oxaliplatin. The patients underwent either a low anterior resection (LAR) or an abdominoperineal resection (APR) after completion of NCRT. Two experienced colorectal surgeons performed the procedures according to total mesorectal excision principles, and the height of the inferior mesenteric artery was taken into account. No extended lateral lymph node dissections were performed. If necessary, extra-anatomic resections and ileostomies were performed. The median interval between neoadjuvant chemotherapy and surgery was 7.3 weeks (range 4 to 13 weeks). Carbon nanoparticle injection In the CNP group, 0.5 mL of CNP suspension (0.5 mL: 25 mg, Chongqing LUMMY Pharmaceutical Co) was injected into the submucosal layer using a rectal speculum at 3 points around the primary tumor 1 day before surgery. Pathologic examination All lymph nodes were manually harvested from fresh specimens before formalin fixation by the same assistant, who had participated in a study of lymph node yields in colorectal cancer and who was accustomed to finding as many lymph nodes as possible. Standard pathologic tumor staging of the specimens was performed by dedicated gastrointestinal cancer pathologists via routine hematoxylin-eosin staining for identification of involved lymph nodes according to the guidelines of the College of American Pathologists.14 Statistical analysis Data are presented as mean ( SD) for continuous variables and as frequency (%) for categorical variables. Differences between groups were compared by the Mann-Whitney U test for continuous variables and the chi-square test or Fisher’s exact test for categorical variables. Univariate and multivariate logistic regression models were used to evaluate the association between the number of lymph nodes harvested and the rate of node positivity. A p value < 0.05 was considered significant. All statistical analyses were performed with SPSS for Windows (version 17.0, SPSS Inc).
RESULTS Patient characteristics A total of 152 patients were included in the analysis. The mean age of the subjects was 53.7 years (range 32 to 78 years), and 113 (74.3%) patients were men. Ninety-one (59.9%) patients underwent LAR, and 61 (40.1%) patients had APR. A laparoscopic technique was used in
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Clinicopathologic Characteristics of the Two Groups of Patients
Characteristic
Sex Male Female Age, y, mean SD Neoadjuvant treatment 5-FU monotherapy 5-FU/oxaliplatin Tumor site, cm <6 612 Tumor size, cm* <2.5 2.5 Type of operation LAR APR Pre-treatment stagey II III Postoperative stagey 0 I II III Postoperative T stagey T0 T1 T2 T3 T4 Tumor differentiation Well to moderate Poorz Lymph nodes, n, mean SD
Total (n ¼ 152)
Carbon nanoparticle group (n ¼ 45)
Control group (n ¼ 107)
p Value
113 (74.3) 39 (25.7) 53.7 11.7
34 (75.6) 11 (24.4) 53.1 12.0
79 (73.8) 28 (26.2) 54.0 11.6
0.824
60 (39.5) 92 (60.5)
18 (40) 27 (60)
42 (39.3) 65 (60.7)
79 (52.0) 73 (48.0)
23 (51.1) 22 (48.9)
56 (52.3) 51 (47.7)
77 (50.7) 75 (49.3)
18 (40.0) 27 (60.0)
59 (55.1) 48 (44.9)
91 (59.9) 61 (40.1)
29 (64.4) 16 (35.6)
62 (57.9) 45 (42.1)
53 (34.9) 99 (65.1)
14 (31.1) 31 (68.9)
39 (36.4) 68 (63.6)
16 51 48 37
(10.5) (33.6) (31.6) (24.3)
8 9 12 16
(17.8) (20) (26.6) (35.6)
8 42 36 21
(7.5) (39.3) (33.6) (19.6)
16 28 32 72 4
(10.5) (18.4) (21.1) (47.4) (2.6)
8 6 6 24 1
(17.8) (13.3) (13.3) (53.3) (2.2)
8 22 26 48 3
(7.5) (20.6) (24.3) (44.9) (2.8)
0.674 0.931
0.890
0.088
0.455
0.528
0.014
0.124
0.422 121 (79.6) 31 (20.4) 11.9 8.8
34 (75.6) 11 (24.4) 21.1 9.6
87 (81.3) 20 (18.7) 8.0 4.6
0.000
Data presented as n (%) unless otherwise indicated. *Largest tumor diameter. y T and N stages according to the American Joint Committee on Cancer 7th ed. z Including mucinous, signet-ring cell carcinoma. APR, abdominoperineal resection; LAR, low anterior resection.
147 (97%) cases. After NCRT, downstaging was observed in 27 (60%) patients in the CNP group and 80 (74.8%) patients in the control group (p ¼ 0.014). The mean number of lymph nodes harvested in all patients was 11.9 (range 1 to 44), and pathologic tumor staging identified 37 (24.3%) patients with lymph node metastases. The patients’ clinicopathologic characteristics are shown in Table 1.
Relationship between the number of nodes harvested and the node positivity rate The numbers of lymph nodes harvested were categorized into 4 groups (1 to 5, 6 to 8, 9 to 16, and 17 to 44) according to the interquartile range for each patient. The rate of node positivity increased gradually, from 8.6% in patients with 1 to 5 nodes harvested to 37.8% in patients with 17 to 44 nodes harvested. The positive correlation between the
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Figure 1. Relationship between the number of lymph nodes harvested and the node positivity rate.
number of nodes and node positivity was monotonic, with no plateau (Fig. 1). To evaluate the relationship between the number of lymph nodes harvested and node positivity, univariate and multivariate logistic regression analyses were performed. As shown in Table 2, the number of lymph nodes harvested was found to be an independent risk factor for the rate of node positivity (p ¼ 0.113) after adjusting Table 2.
for several confounding variables, including T stage and tumor differentiation. Effect of carbon nanoparticle staining on lymph node detection As shown in Table 3, for the CNP group, the mean time for lymph node retrieval was shorter than that in the
Univariate and Multivariate Analyses of Factors Influencing Lymph Node Metastases in This Cohort
Factors
Sex (male/female) Age, y (>65 vs 65) Site, cm (6 vs <6) Surgery (APR vs LAR) Tumor size, cm* (2.5 vs <2.5) Postoperative T stagey (yp T3-4 vs yp T0-2) Neoadjuvant treatment (5-FU/oxaliplatin vs 5-FU monotherapy) Interval, wk <6 6e8 >8 Tumor differentiation (poorz, vs well to moderate) Lymph node retrieval 1e5 6e8 9e16 17e44
Univariate analysis Odds ratio p Value
1.10 0.26 0.78 1.37 2.32
(0.48e2.54) (0.06e1.15) (0.37e1.64) (0.65e2.90) (1.07e5.00)
4.34 (1.88e10.03) 0.94 (0.44e2.02) 1 0.67 (0.29e1.51) 0.29 (0.09e0.92) 9.06 (3.76e21.83) 1 1.94 (0.45e8.42) 5.53 (1.44e21.29) 6.49 (1.67e25.23)
0.827 0.075 0.504 0.408 0.032 0.001 0.879 0.104 d 0.329 0.036 0.000 0.012 d 0.377 0.013 0.007
*Greatest tumor diameter. y T and N stages according to the American Joint Committee on Cancer 7th ed. z Including mucinous, signet-ring cell carcinoma. APR, abdominoperineal resection; LAR, low anterior resection; yp, pathologic stage after neoadjuvant chemoradiation.
Multivariate analysis Odds ratio p Value
1.56 (0.63e3.91)
0.339
3.34 (1.30e8.63)
0.012
8.98 (3.25e24.80)
0.000 0.036 d 0.113 0.008 0.009
1 3.82 (0.73e20.08) 8.07 (1.72e37.87) 8.02 (1.68e38.31)
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Lymph Node Dissections in the Two Groups Carbon nanoparticle group
Variable
Time required for LN retrieval, min, mean SD LN count, mean SD Patients, n (%) LN <12 LN 12 LN status N0 Nþ
Control group
p Value
27.6 3.5 34.6 4.3 0.000 21.1 9.6 8.0 4.6 0.000 5 (11.1) 40 (88.9)
84 (78.5) 23 (21.5)
0.000 0.037
29 (64.4) 16 (35.6)
86 (80.4) 21 (19.6)
LN, lymph node.
control group (27.6 vs 34.6 minutes, p ¼ 0.000). A comparison of the number of lymph nodes detected between the control and the CNP groups is presented in Table 3. The mean number of lymph nodes retrieved differed markedly, ranging from 21.1 in the CNP group to 8.0 in the control group (p ¼ 0.000). Furthermore, the percentage of patients with a minimum of 12 lymph nodes was 88.9% in the CNP group, which was significantly higher than the rate of 21.5% in the control group (p ¼ 0.000). Additionally, the node positivity rate was 35.6% (16 of 45) in the CNP group, which was higher than the 19.6% (21 of 107) node positivity rate in the control group (p ¼ 0.037). In the CNP group, all patients were successfully traced with CNPs (Fig. 2), and there were no reports of acute or chronic systemic toxicity. The rates of dyed nodes were 84.8% (806 of 951) for all lymph nodes and 87.5% (538 of 615) for lymph nodes smaller than 5 mm. Among the 58 metastatic lymph nodes, 45 (77.6%) were dyed, and of the 37 metastatic lymph nodes smaller than 5 mm, 33 (89.2%) were dyed (Table 4).
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DISCUSSION Accurate evaluation of a patient’s node status is important because lymph node involvement has been widely reported as one of the strongest determinants of survival in patients with rectal cancer treated with NCRT.15,16 Reliable nodal staging of rectal cancer requires detection and evaluation of a certain number of nodes.17 However, as reported in previous studies, NCRT significantly reduces the number of lymph nodes harvested, with fewer than 12 nodes detected per specimen on average.17,18 Because of the National Comprehensive Cancer Network (NCCN) recommendation that all patients receiving adjuvant chemotherapy complete 6 months of treatment, including NCRT, regardless of downstaging after neoadjuvant treatment and surgery,19 there has been little interest in studying the association between the number of nodes harvested and the rate of node positivity. In recent years, however, an increasing number of studies have shown that adjuvant chemotherapy after surgery is not beneficial for patients with pathologic complete responses or yp stage I/II.10,11,20,21 These results indicate the importance of evaluating the association between the number of nodes harvested and the rate of node positivity after NCRT to improve the accuracy of nodal staging. In this study, the numbers of lymph nodes harvested were categorized into 4 intervals (1 to 5, 6 to 8, 9 to 16, and 17 to 44) according to the interquartile range of each patient. The rate of node positivity increased gradually, with corresponding increases in the number of harvested lymph nodes. This result is in agreement with reports by Kim and colleagues8 and Persiani and associates.22 However, because of the limited number of patients in our study, we were unable to obtain a sufficient number of harvested lymph nodes to reach a stable rate of node positivity. Nevertheless, the univariate and multivariate logistic regression analyses showed that
Figure 2. (A) Specimen and the dyed lymph nodes (arrows) and (B) harvested lymph nodes.
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Table 4. Detection of Lymph Nodes and Metastatic Lymph Nodes in the Carbon Nanoparticle Group
Variable
Stained metastatic LNs n %
Overall, n
Stained LNs n %
Metastatic LNs, n
951 45
806 84.8 45 100
58 16
45 16
77.6 100
336 615
268 538
21 37
12 33
57.1 89.2
Overall LNs Patients LN size, mm 5 <5
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79.8 87.5
LN, lymph node.
the number of lymph nodes harvested was an independent risk factor for node positivity and that N stage should be underestimated because of omission of positive lymph nodes in patients from whom fewer lymph nodes are harvested. This result may explain the finding of nodenegative patients with 6 or fewer harvested lymph nodes who had significantly poorer disease-free survival (DFS) and overall survival (OS) in La Torre and coworkers’ study.23 Because it is necessary to harvest more lymph nodes to attain accurate N staging, suitable postoperative chemotherapy recommendations, and a precise oncologic prognosis, it is important to find a simple and effective method to obtain more lymph nodes from a specimen after NCRT and to enhance the rate of node positivity. The fat clearance technique has been reported to improve lymph node harvesting and the accuracy of staging,24 but it is not suitable for daily practice due to the additional laboratory procedures, time required, and its potential hazards. Alternatively, in Okada and coauthors’ study,25 preoperative tracing using India ink was shown to increase the number of retrieved lymph nodes in patients after NCRT (14 vs 8, p < 0.01). Carbon nanoparticles are another widely used lymph node tracer in patients with thyroid and gastrointestinal
cancers, and this tracer has better lymphotropic effects and a slower metabolic velocity than ink.12,26 In a previous study, we found that submucosal CNP staining could improve lymph node retrieval from gastrointestinal carcinomas without additional operative or pathologic time requirements.12 In this study, we also discovered that more lymph nodes were harvested more rapidly when submucosal CNP staining was used. In particular, beginning in August 2013, preoperative submucosal CNP staining was used in 45 patients. For these 45 patients, the mean number of harvested nodes was 21.1, which was significantly greater than the per-patient mean of 8.0 lymph modes harvested in patients who were not administered CNPs (p ¼ 0.002). Meanwhile, the mean time spent on lymph node retrieval was 27.6 minutes in the CNP group, which was significantly less than that in the control group (34.6 minutes). Due to the increase in the number of lymph nodes harvested, 35.6% of cases were identified as yp stage III in the CNP group, which was significantly higher than the rate in the control group (19.6% of cases; p ¼ 0.037). In this study, pre-treatment staging and NCRT protocols were consistent between the CNP and the control groups, but we discovered less downstaging in the CNP group, which might have been due to underestimation of the lymph node metastasis rate in the control group. Therefore, the application of CNPs might favor more accurate postoperative N staging, and a more appropriate decision about postoperative chemotherapy could be made accordingly, which would eventually help us to predict patient prognoses more precisely. It has been suggested that a decrease in the size of lymph nodes (<5 mm) caused by lymphocyte destruction or atrophy of the stroma due to NCRT is the main reason for the reduced number of lymph nodes harvested from specimens processed by conventional manual retrieval.27 Through analysis of lymph nodes from patients in the CNP group, approximately 64.7% (615 of 951) of lymph
Figure 3. Rectum with (A) an accurately dyed layer and (B) with an excessively dyed layer.
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node diameters were found to be <5 mm, and these were difficult to identify using visual-tactile methods. This result demonstrates that after NCRT, most lymph nodes do not disappear, but are instead reduced in size.28 These lymph nodes are more difficult to detect but are still present.29 As a good tracer of lymph nodes, CNPs were able to dye approximately 84.8% (806 of 951) of lymph nodes in the present study. Among nodes with diameters <5 mm, 87.5% (538 of 615) were dyed, suggesting that CNPs play an important role in the detection of small nodes that can be overlooked during conventional manual detection. We found that 6.0% (37 of 615) of these small lymph nodes were metastatic. Of these small metastatic lymph nodes, approximately 89.2% (33 of 37) were stained by CNPs. This finding may account for the higher node positivity rate in the CNP group than in the control group. To sufficiently stain the lymph nodes, we used a long needle to conduct a peri-tumor, 3-point submucosal injection of CNPs through a rectal speculum 1 day before surgery. Because the inferior tumor margin could be observed through the rectal speculum in mid-low rectal cancer patients, the injection method was easily conducted in the ward without further endoscopy, which is both beneficial to patients and welcomed by surgeons. The key aspect of this method lies in the accurate injection of CNPs into the submucosal layer, rather than into the mesorectum or the pararectal space. Otherwise, the identification of pararectal lymph nodes (6 patients) and the intraoperative identification of fascias and spaces (4 patients) would be negatively affected (Fig. 3). We injected saline into the submucosa to expand the layer and to facilitate subsequent CNP injection. Our study has certain limitations. First, we began to use CNPs for lymph node staining and collection in August 2013; therefore, we had to use retrospective data from the colorectal cancer database13 at Nanfang Hospital that were obtained before this point. Second, because only a moderate number of patients were included in this study, the optimal number of lymph nodes required to stage patients with locally advanced rectal cancer treated with NCRT is unclear. Therefore, a large-scale prospective study is necessary to further confirm these results.
CONCLUSIONS In conclusion, more accurate N staging and more precise oncologic prognosis assessment were achieved for patients with rectal cancer following NCRT by increasing the number of lymph nodes counted using a dye-tracing method, indicating that the use of CNPs is beneficial.
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Author Contributions Study conception and design: Wang, Li Acquisition of data: Deng, Chen Analysis and interpretation of data: Liu, Xue Drafting of the manuscript: Wang, Li Critical revision: Yan, Li REFERENCES 1. Edge SB, Compton CC. The American Joint Committee on Cancer: the 7th edition of the AJCC cancer staging manual and the future of TNM. Ann Surg Oncol 2010;17: 1471e1474. 2. Nelson H, Petrelli N, Carlin A, et al. Guidelines 2000 for colon and rectal cancer surgery. J Natl Cancer Inst 2001;93: 583e596. 3. Washington MK, Berlin J, Branton PA, et al. Protocol for the examination of specimens from patients with primary carcinomas of the colon and rectum. Arch Pathol Lab Med 2008;132:1182e1193. 4. Kapiteijn E, Marijnen CA, Nagtegaal ID, et al. Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer. N Engl J Med 2001;345:638e646. 5. Ha YH, Jeong SY, Lim SB, et al. Influence of preoperative chemoradiotherapy on the number of lymph nodes retrieved in rectal cancer. Ann Surg 2010;252:336e340. 6. Morcos B, Baker B, Al Masri M, et al. Lymph node yield in rectal cancer surgery: effect of preoperative chemoradiotherapy. Eur J Surg Oncol 2010;36:345e349. 7. Baxter NN, Morris AM, Rothenberger DA, Tepper JE. Impact of preoperative radiation for rectal cancer on subsequent lymph node evaluation: a population-based analysis. Int J Radiat Oncol Biol Phys 2005;61:426e431. 8. Kim NK, Baik SH, Seong JS, et al. Oncologic outcomes after neoadjuvant chemoradiation followed by curative resection with tumor-specific mesorectal excision for fixed locally advanced rectal cancer: Impact of postirradiated pathologic downstaging on local recurrence and survival. Ann Surg 2006;244:1024e1030. 9. Ishihara S, Watanabe T, Kiyomatsu T, et al. Prognostic significance of response to preoperative radiotherapy, lymph node metastasis, and CEA level in patients undergoing total mesorectal excision of rectal cancer. Int J Colorectal Dis 2010;25: 1417e1425. 10. Haynes AB, You YN, Hu CY, et al. Postoperative chemotherapy use after neoadjuvant chemoradiotherapy for rectal cancer: Analysis of Surveillance, Epidemiology, and End Results-Medicare data, 1998-2007. Cancer 2014;120: 1162e1170. 11. Geva R, Itzkovich E, Shamai S, et al. Is there a role for adjuvant chemotherapy in pathological complete response rectal cancer tumors following neoadjuvant chemoradiotherapy? J Cancer Res Clin Oncol 2014;140:1489e1494. 12. Chen H, Wang Y, Xue F, et al. [Application of subserosal injection of carbon nanoparticles via infusion needle to label lymph nodes in laparoscopic radical gastrectomy]. Zhonghua wei chang wai ke za zhi (Chinese J Gastrointest Surg) 2014; 17:457e460. 13. Liang YZ, Yu J, Zhang C, et al. [Construction and application of evaluation system of laparoscopic colorectal surgery based
8
14.
15.
16.
17.
18. 19. 20. 21.
Wang et al
Carbon Nanoparticles in Rectal Cancer
on clinical data mining]. Zhonghua wei chang wai ke za zhi (Chinese J Gastrointest Surg) 2010;13:741e744. Washington MK, Berlin J, Branton P, et al. Protocol for the examination of specimens from patients with primary carcinoma of the colon and rectum. Arch Pathol Lab Med 2009; 133:1539e1551. Leibold T, Shia J, Ruo L, et al. Prognostic implications of the distribution of lymph node metastases in rectal cancer after neoadjuvant chemoradiotherapy. J Clin Oncol 2008;26: 2106e2111. Chang GJ, Rodriguez-Bigas MA, Eng C, Skibber JM. Lymph node status after neoadjuvant radiotherapy for rectal cancer is a biologic predictor of outcome. Cancer 2009;115: 5432e5440. Rullier A, Laurent C, Capdepont M, et al. Lymph nodes after preoperative chemoradiotherapy for rectal carcinoma: number, status, and impact on survival. Am J Surg Pathol 2008;32: 45e50. Scott N, Thorne C, Jayne D. Lymph node retrieval after neoadjuvant radiotherapy for rectal adenocarcinoma. J Clin Pathol 2004;57:335e336. Rectal cancer, NCCN guidelines. Available at: http://www. nccn.org/professionals/physician_gls/pdf/rectal.pdf version 3. Accessed September 2, 2015. Gao P, Song YX, Sun JX, et al. Which is the best postoperative chemotherapy regimen in patients with rectal cancer after neoadjuvant therapy? BMC Cancer 2014;14:888. Sainato A, Cernusco Luna Nunzia V, Valentini V, et al. No benefit of adjuvant Fluorouracil Leucovorin chemotherapy after neoadjuvant chemoradiotherapy in locally advanced cancer of the rectum (LARC): Long term results of a randomized trial (I-CNR-RT). Radiother Oncol 2014;113:223e229.
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22. Persiani R, Biondi A, Gambacorta MA, et al. Prognostic implications of the lymph node count after neoadjuvant treatment for rectal cancer. Br J Surg 2014;101:133e142. 23. La Torre M, Mazzuca F, Ferri M, et al. The importance of lymph node retrieval and lymph node ratio following preoperative chemoradiation of rectal cancer. Colorectal Dis 2013;15: e382ee388. 24. Gehoff A, Basten O, Sprenger T, et al. Optimal lymph node harvest in rectal cancer (UICC stages II and III) after preoperative 5-FU-based radiochemotherapy. Acetone compression is a new and highly efficient method. Am J Surg Pathol 2012;36: 202e213. 25. Okada K, Sadahiro S, Suzuki T, Tanaka A, Saito G, Kamijo A. Use of preoperative tattooing to increase lymph nodes (LNs) retrieved in patients with locally advanced rectal cancer who receive preoperative chemoradiotherapy (CRT): A randomized controlled trial. J Clin Oncol 2014;32:561. 26. Shen H, Wei B, Feng S, Zhou Q. [Efficiency of carbon nanoparticles in level VI lymphadenectomy for thyroid carcinoma and prevention of postoperative hypoparathyroidism]. Zhonghua er bi yan hou tou jing wai ke za zhi (Chinese J Otorhinolaryngol Head Neck Surg) 2014;49:817e820. 27. Shvero J, Koren R, Marshak G, et al. Histological changes in the cervical lymph nodes after radiotherapy. Oncol Rep 2001; 8:909e911. 28. Kim JS, Sohn DK, Park JW, et al. Prognostic significance of distribution of lymph node metastasis in advanced mid or low rectal cancer. J Surg Oncol 2011;104:486e492. 29. Farinella E, Vigano L, Fava MC, et al. In vivo lymph node mapping and pattern of metastasis spread in locally advanced mid/low rectal cancer after neoadjuvant chemoradiotherapy. Int J Colorectal Dis 2013;28:1523e1529.