Evaluation of Relapse-Free Survival in T3N0 Colon Cancer: The Role of Chemotherapy, a Multicentric Retrospective Analysis

578 Background: Use of adjuvant chemotherapy (AC) in stage II colon cancer (CC) is still under debate. Choice should be based on patients (pts) and disease characteristics. According to worldwide guidelines AC should be considered in high-risk (H) T3N0 pts. No data are available for better option in low-risk (L) pts. Aim of the study is to evaluate relapse-free survival (RFS) and disease-free survival (DFS) retrospectively in T3N0 CC pts related to treatment. METHODS RFS and DFS are evaluated with Kaplan Meier method. In order to find the optimal cut off for node number the receiver operating characteristics curve analysis and maximally selected rank statistics were performed. Multivariate Cox proportional hazard model was developed using stepwise regression, enter limit and remove limit were p = 0.10 and p = 0.15 respectively. RESULTS 1,000 pts with T3N0 CC were recruited. To date, data of 764 pts are available. Median age was 68 (29-93), M/F 42/344, grading 1/2/3 40/561/132; 303 L (40%), 356 H (46%), 105 unknown (14%); 121 (16%) pts showed symptoms (S) at diagnosis: 43 pts had perforation (P) or bowel obstruction (BO). Median sampled lymph nodes (LN) were 15 (1-76); 339 (44%) pts were treated with AC. Median follow up (fu) was 5 years (yr) (range 3-24). Survival analysis analysis was performed only for pts with a minimum fu of 3 yr and younger than 80 (79%). 5 yr RFS was 79% and 5 yr DFS was 77%. At multivariate analysis S, LN and AC were prognostic factors for RFS. AC is prognostic factor for all endpoints (Table). In L group 5 yr RFS was 88% in treated pts and 71% in non-treated pts (p 0.004); in H group was respectively 84% and 70% (p 0.002). CONCLUSIONS Preliminary data confirmed the role of known prognostic factors and suggest the relevance of AC also in L stage II T3N0 CC pts. However, the highest risk in L subgroup should be identified to be submitted to AC. Data collection is ongoing. [Table: see text].