Abstracts left, 18.2% right, 37.1% unknown. Mutation analysis of AYAp showed: no mutations of KRAS 58/78 (74.4%), NRAS 9/11 (81.8%), and BRAF 9/12 (75%) patients. Total 104 AYAp received 1st-line chemotherapy for metastatic CRC: CAPOX/FOLFOX n = 80, CAPIRI/FOLFIRI n = 10, FLOX n = 5, FOLFIRINOX n = 3 with concurrent bevacizumab n = 63, cetuximab n = 7, panitumumab n = 3. Total of 81 (61.3%) underwent surgical intervention throughout their course of treatment. Hazard ratios showed no association between age group and OS, PFS 2 as it demonstrated adjusted HR of 1.26 (95% CI: 0.70–2.26) and 1.19 (95% CI:0.66–2.15) respectively. However, association was seen in PFS 1 with adjusted of HR 2.00 (95% CI: 1.22–3.28). (Table 1) Conclusion: Both AYAp and MATp had similar OS, in line with published literature. However, association between age groups in PFS 1 may illustrate more aggressive nature of CRC in AYAp subgroup. Further collaboration analyzing AYAp with CRC is required to better elucidate treatment patterns and outcomes. No conflict of interest. 2055 POSTER Tumor size as a prognostic factor in patients with IIa stage colon cancer F. Santullo1 , R. Persiani1 , A. Biondi1 , C. Coco1 , G. Rizzo2 , D. D’Ugo1 . 1 Catholic University of The Sacred Heart, Surgery, Roma, Italy; 2 Complesso Integrato Columbus, surgery, Rome, Italy Background: Resection is the gold standard treatment in most of T1−3N0 (stage I-IIa) colon cancer (CC) patients, conversely, it is currently matter for debate the administration of adjuvant treatment among this group of patients. The aim of the study was to identify patients with higher risk of recurrence who could benefit from post-operative chemotherapy. Material and Methods: All patients, with stage I and IIa CC, who underwent surgical resection from 2003 to 2011, were retrospectively enrolled in the study. High risk IIa stage patients with poor prognostic features (G3, lymphovascular invasion, obstruction, perforation, R1 or R2 resection and less than 12 harvested lymph nodes) who underwent postoperative chemotherapy were excluded from the study. The primary outcomes measured were 5-years overall (OS) and diseasefree survival (DFS). Factors considered for analysis were: sex, age at diagnosis, tumor location, median value of the maximum tumor diameter (DMAX), serum preoperative CEA level, total number of lymph nodes resected, charlson comorbidity, BMI, hemoglobin level, smoke. Moreover, the DFS of IIa stage CC was compared with the outcome of high risk IIa, IIb/c stage CC treated at the same institution. Results: During the study period 225 patients with a diagnosis of stage I and IIa CC underwent surgical resection. One hundred and eleven stage I and 114 IIa CC patients were reviewed. Follow-up data were available for all patients. Median follow-up was 39 months. Five-years OS and DFS were 97.2% and 96.5% respectively. At survival analysis in stage I patients we could not identify any significant prognostic factor. On univariable analysis in IIa stage only DMAX <4cm (5 yrs DFS 71.7% vs. 87.6% − p:0.028) was associated with statically worse DFS. On univariable Cox regression analysis DMAX <4cm was associated with an increased risk of recurrence (HR: 3.436; 95% Confidence Interval: 1,058–11.161; p: 0.04). All IIa stage patients were divided into 2 groups, according to DMAX (small CC and large CC). In the same period 100 high risk IIa, IIb/c were treated. Median follow-up was 47.5 months, and five-years DFS was 78.3%. Seventy-nine patients received adjuvant chemotherapy. Moreover, the outcome of small and large IIa stage CC were compared with the outcome of high risk IIa, IIb/c stage CC. DFS in large IIa CC was significantly better than high risk IIa, IIb/c (5 years DFS 92.7% vs 79.3% − p: 0.023). Instead, at survival analysis recurrence rate in small IIa CC was similar to high risk IIa, IIb CC (5 years DFS 71.7% vs 79.3% − p: 0.839). Conclusions: For patients with stage IIa CC treated with resection alone, evaluation of tumor size as a prognostic factor may help identify those patients who could benefit from additional postoperative therapy. No conflict of interest. 2056 POSTER Locally advanced rectal cancer with neoadyuvant treatment strategies: Our experiences M.L. Blanco Villar1 , A. Rodriguez Gutierrez1 , A. Nieto Palacio1 , A. Matias Perez1 , P. Soria Carreras1 , V.M. Macias Hernandez1 , O. Alonso Rodriguez1 , M. Sanchez Barba1 , L.A. Perez Romasanta1 , J. Garc´ıa2 . 1 Hospital Universitario, Radiation Oncology, Salamanca, Spain; 2 Hospital Universitario, Surgery, Salamanca, Spain Background: Preoperative chemo-radiotherapy (CRT) followed by radical surgery, has emerged as the preferred treatment for locally advanced rectal cancer.
S347 This study reports outcomes of patients with locally advanced rectal cancer with (CRT) followed by surgery. The Primary end-point was evaluation of toxicity, compliance with radiotherapy and chemotherapy, downstaging, pathological complete response and the rate of sphincter preservation for distal cancers. Secondary end-point was report local control and distant relapse. Methods: Present a single-centre retrospective study of consecutive patients with clinical stage II − III rectal adenocarcinoma that received preoperative treatment with short-course radiotherapy (25 Gy in 5 daily fractions) or long-course radiotherapy (45−46 Gy in 25 fractions) with concomitant chemotherapy based in fluoropirimidines. The study group consisted of 275 (171 males, 104 females) retrospectively accrued patients with locally advanced rectal cancer treated from 2004 to 2015 at our institution. Median age at diagnosis was 71 years. All patients had biopsy-proven rectal adenocarcinoma. Results: All of them completed radiotherapy. The median time of radiotherapy was 5 weeks. The elder patients who couldn’t receive chemotherapy were only 6,9% (19 of 275 patients) and they had received short-course radiotherapy. The rest of them received long-course radiotherapy. Most of patients received preoperative chemotherapy (230 of 275) using capecitabine in the most of cases. The toxicity was evaluated using RTOG/EORTC toxicity criteria. Acute toxicity was observed in 160 patients (60,2%). We reported gastrointestinal acute toxicity in 49% of patients (grade 1 in 29,2% of them and grade 2 in 21%). The most common toxicity was gastrointestinal. There were only 2 patients with acute gastrointestinal toxicity grade 3. The genitourinary acute toxicity and skin reactions were less observed. Surgery was performed in 264 patients with 88,2% R0 resection (Table 1). The median time to surgery was 8 weeks. 68,7% (189 of 264) of patients achieved pathological downstaging and 14’8% (28 of 189) had a pathologic complete response. In 110 patients the localization of tumor was in lower part of rectum. 25 of these patients had anterior resection (22’7%) allowing the preservation of the anal sphincter. Table 1. Surgical status Surgical status
Frequency
Percentage
R1 R2 R0 Irresectable Total
16 7 232 8 264
6.1 2.7 88.2 3.0 100
At median follow-up was a 2.5 year. 40 patients (14.5%) had a local relapse. 56 (20.6%) had distant relapse. Conclusions: We believe that locally advance rectal cancer can be managed satisfactory with chemo-radiotherapy followed surgery. Our study provides right evidence that neoadyuvant treatment for rectal cancer was safe and well tolerated with right local control and distant relapse. We report right rates of downstaging and pathological complete response. Data on sphincter preservation for distal cancers were excellent. No conflict of interest. 2057 POSTER Assessment of tumor-infiltrating lymphocytes in metastatic colorectal cancer patients treated by Bevacizumab-based chemotherapy J.P. Spano1 , A. Gobert2 , C. Mateescu2 , R. Mouawad3 , A. Bardier4 , J.B. Bachet5 , O. Dubreuilh5 , J. Varinot6 , R. Mitri5 , D. Khayat3 , G. Malouf3 , ´ ˆ ere ` University Hospital − INSERM UMR_S F. Capron7 . 1 Pitie-Salp etri 1136, GHPS-CFX, APHP, IUC/UPMC, Medical Oncology, Paris, France; 2 ´ ˆ ere, ` Groupe Hospitalier Pitie-Salp etri Medical Oncology, Paris, France; 3 ´ ˆ ere ` Hospital, GRC5 IUC/UPMC, Medical Oncology, Paris, Pitie-Salp etri 4 ´ ˆ ere, ` France; Groupe Hospitalier Pitie-Salp etri Anatomy Pathology, Paris, ´ ˆ ere, ` France; 5 Groupe Hospitalier Pitie-Salp etri Internal Medecine, Paris, 6 ´ ˆ ere, ` France; Groupe Hospitalier Pitie-Salp etri anatomy patologic, Paris, 7 ´ ˆ ere-UPMC, ` France; Groupe Hospitalier Pitie-Salp etri Anatomy Pathology, Paris, France Background: Previous studies recently demonstrated that the immune system dictates prognosis and response to chemotherapy in several tumor subtypes. Furthermore, programmed death-1 (PD-1) has become a potential target in oncology. However, it remains unknown if the expression of tumor-infiltrating cells (TIL) and PD-1 can predict outcome of patients with metastatic colorectal cancers treated by Bevacuzimab-based chemotherapy. Methods: We analyzed the correlation between the quantity and location of lymphocytic infiltrate (primary and metastasis) in a large cohort of colorectal