2053 Nomogram and recursive partitioning analysis to determine the risk of cancer-specific survival for patients with stage II or III upper rectal cancer after radical surgery

S346 had optimal (27) or incomplete (34) response by CTMC (91%, 95% CI 82−96%). Complete (12) or major (30) pR was achieved in 42 of 51 pts (82%, 95% CI 70−90%). RECIST partial response was observed in 16/35 (46%, 95% CI 29−63%) wild-type KRAS pts and in 16/31 (52%, 95% CI 33−70%) pts with KRAS mutation (p=.63). Morphologic response (optimal/ incomplete) was similar in wild-type (31/35, 89%, 95% CI 73−97%) and mutant (28/30, 93%, 95% CI 78−99%) KRAS patients (p=.68). Regarding pR (complete/major), no significant association was observed according to the pt’s KRAS status: 25/29 (86%, 95% CI 68−96%) in wild-type versus 17/22 (77%, 95% CI 55−92%) in mutants (p=.47). Conclusions: Among pts with CLM treated with BVZ-containing chemotherapy, an outstanding complete or major pR was reached. No significant association was found between basal KRAS status and responses. No conflict of interest. 2052 POSTER Efficacy and safety of oxaliplatin combined with capecitabine as neoadjuvant chemotherapy for locally advanced operable colon cancer patients: A prospective phase II trial (NCT02415829) F. Liu1 , L. Yang1 , D. Huang2 , L. Wang2 , J. Xu3 , Y. Xu1 . 1 Fudan University, Shanghai Cancer Center, colorectal surgery, Shanghai, China; 2 Fudan University, Shanghai Cancer Center, pathology, Shanghai, China; 3 Fudan University, Shanghai Cancer Center, medical imageology, Shanghai, China Aim: Preoperative (neoadjuvant) chemotherapy and radiotherapy are more eff ective than similar postoperative treatment for rectal cancers, perhaps because of more effective micrometastasis eradication and reduced risk of incomplete excision and tumour cell shedding during surgery. This study was a prospective, single-arm phase II trial to assess the efficacy and safety of Oxaliplatin combined with Capecitabine as neoadjuvant chemotherapy for locally advanced colon cancer patients. Methods: Patients with CT-defined T4 or lymph node-positive colon cancer were enrolled. After radiological staging, patients were treated with 3 cycles of neoadjuvant chemotherapy consisting of oxaliplatin, 130 mg/m2 on day 1, with capecitabine, 1000 mg/m2 twice daily for 14 days every 3 weeks (the XELOX regimen), followed by tumor resection, and then with another 5 cycles of adjuvant chemotherapy with the XELOX regimen. Radiological response was evaluated after 2 cycles of neoadjuvant chemotherapy. A total of 3 cycles neoadjuvant chemotherapy was completed unless there was unacceptable toxicity, emergency operation condition or tumor progression during the period. Tumor responses, toxicities, and surgical complications were recorded. The pathological tumor response in the primary tumor was evaluated according to tumor regression grade (TRG) score. The primary endpoints were tumor response rate. This trial is registered with ClinicalTrials.gov, number NCT02415829. Results: Forty-eight patients were enrolled and received treatment. All the patients received 3 cycles of neoadjuvant chemotherapy and R0 resection. The total clinical response rate was 66.7% (32/48) including a complete response and partial response rate of 4.2% (2/48) and 62.5% (30/48), respectively. Stable disease was observed in 33.3% (16/48) of patients and no progressive disease in all patients. The total pathological response rate was based on TRG score. PCR(TRG0), major regression(TRG1) and at least moderate regression(TRG2) were achieved in 2 (4.2%), 5 (10.4%), and 34 patients (70.8%), respectively. Hematological toxicities were the major toxicities and grade 3/4 neutropenia developed in only one patients. Emergency operation condition were observed in one patient with perforation and another with obstruction. Operation complications rate was 4.2% (2/48) with wound infection and mortality rate was 0. Conclusions: Preliminary results suggest that neoadjuvant chemotherapy with XELOX is a effective and safe treatment for patients with locally advanced colon cancer. No conflict of interest.

Abstracts Material and Methods: This retrospective analysis included 547 primary URC patients who were extracted from 3995 rectal cancer patients admitted in Cancer Hospital, Chinese Academy of Medical Sciences from January 2000 to December 2010. Lower margin of the tumor located 10−16cm from the anal verge determined by colonoscope, underwent radical resection (R0) and pathologically staged as II/III were included. A nomogram was developed based on the Cox regression model predicting 5-year CSS and RPA stratified patients into risk groups based on their tumor characteristics. Kaplan–Meier curves were used to estimate CSS rates in each risk group according to ACRT or ACT status. Results: With a median follow-up of 68 months (range 4.6–182.5), the actually 5-year overall survival, disease-free survival, CSS, local recurrence free survival and distant metastasis free survival of the entire cohort were 79.7%, 76.1%, 83.3% and 93.7% and 79.8%, respectively. Of the 547 patients, 379 (69.3%) received ACRT or adjuvant radiotherapy and 327 (59.9%) patients received ACT. Five independent prognostic factors including age, preoperative increased levels of CEA and CA19-9, number of positive lymph nodes (PLNs), tumor deposit (TD), pathologic T category were identified and entered into nomogram that predicts the probability of 5-year CSS. The bootstrap-corrected c-index was 0.75. When patients were divided into three risk groups on the basis of RPA, only high risk group benefited from both ACRT and ACT (P < 0.001) when compared with surgery alone (P = 0.576) or surgery followd by either ACRT or ACT (P = 0.157): patients with PLNs 6 and TD or PLNs >6. Conclusions: The outcome of URC was definitely good after radical surgery. Our study indicates that surgery followed by ACRT and ACT may be an important treatment plan for high-risk URC with potentially significant survival advantages. No conflict of interest. 2054 POSTER Clinical outcomes of adolescent and young adult patients (AYAp) vs mature adult patients (MATp) with colorectal cancer (CRC), a multi-institutional retrospective review Y.S. Rho1 , M. Gilabert2 , I. Barrera1 , N. Coleman3 , M. Greally3 , R. McDermott3 , V. Megdanova4 , P. Veneta4 , M. Zhasmina4 , K. Kateˇrina5 , Z. Bortlicek6 , T. Pikus5 , L. Zdenek5 , G. Batist1 , P. Kavan1 . 1 Segal Cancer Centre − Jewish General Hospital. McGill University, Medical ´ Canada; 2 Institut Paoli-Calmettes, Medical Oncology, Oncology, Montreal, Marseille, France; 3 St Vincent’s University Hospital, Medical Oncology, Dublin, Ireland; 4 Military Medical Academy, Medical Oncology, Sofia, Bulgaria; 5 2nd Faculty of Medicine, Charles University Prague and Motol University Hospital, Department of Oncology, Prague, Czech Republic; 6 Masaryk University Brno, Institute of Biostatistics and Analysis, Brno, Czech Republic Background: On contrast to the general population, incidence of CRC in AYA is on the rise. However, very little is understood about the clinical patterns and outcomes of CRC in AYAp, especially when compared to MATp. A retrospective data review was performed to further understand the aforementioned. Materials and Methods: A multi-institutional retrospective review was performed by four tertiary institutions. AYAp [18−44 years old (yo)] and MATp (>44 yo) diagnosed with CRC from June 2003-June 2014 were retrieved. Cox proportional hazards models to estimate crude and adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of overall survival (OS), progression-free survival 1 (PFS 1; time from 1st-line treatment to progression or death), and PFS 2 (time from 2nd-line treatment to progression or death), comparing AYAp with MATp. Models conditioned on center, adjusted for sex, primary tumor location, metastasis at diagnosis, T (T of TNM) and year of diagnosis. Table 1. HR for association between age group and OS, PFS1 and PFS2

2053 POSTER Nomogram and recursive partitioning analysis to determine the risk of cancer-specific survival for patients with stage II or III upper rectal cancer after radical surgery X. Wang1 , J. Jin1 , Y. Yang1 , H. Ren1 , W.Y. Liu1 , H. Fang1 , Y.R. Feng1 , Q. Xiao1 , H. Jing1 , L. Deng1 , N. Li1 , Y. Tang1 , N.N. Lu1 , J.Y. Wang1 , S.L. Wang1 , W.H. Wang1 , Y.P. Liu1 , Y.X. Li1 . 1 Cancer Institute & Hospital Chinese Academy of Medical Sciences, Department of Radiation Oncology, Beijing, China Background: Whether adjuvant chemoradiotherapy (ACRT) or chemotherapy (ACT) will benefit for stage II or III upper rectal cancer (URC) after radical surgery remains unclear. The aim of this study was to develop t a clinical nomogram and a recursive partitioning analysis (RPA) based risk stratification system for the prediction of 5-year cancer-specific survival (CSS), trying to reveal whether ACRT or ACT is necessary for these patients.

Age group HR − OS MATp AYAp HR − PFS1 MATp AYAp HR − PFS2 MATp AYAp

# of patients

Incidence rate (95% CI) a

Crude HR (95% CI)

Adjusted HR (95% CI)

97 132

9.7 (6.1–14.5) 16.4 (12.2–21.5)

1.00 (ref) 1.67 (1.01–2.74)

1.00 (ref) 1.26 (0.70–2.26)

57 93

65.7 (47.3–88.7) 92.3 (72.2–116.3)

1.00 (ref) 1.43 (0.98–2.09)

1.00 (ref) 2.00 (1.22–3.28)

49 52

76.7 (52.8–107.8) 130.3 (94.3–175.5)

1.00 (ref) 1.51 (0.95–2.40)

1.00 (ref) 1.19 (0.66–2.15)

a Per 100 Person-years.

Results: Total of 229 patients with CRC, AYAp 132 [median age 37.7 yo (24−44), male 54.6%, median follow up 24.3 months (1.7–91.1)] and 97 MATp [median age 61.7 yo (45−89), male 57.7%, medial follow up 19.9 months (1.2–81.4)] were identified. At diagnosis 63.4% AYAp presented with metastatic disease and primary CRC location were 40.9%