The lymph node ratio as prognostic factor in patients with stage III rectal cancer treated with total mesorectal excision and postoperative chemoradiotherapy

15003 Background: To analyze the prognostic impact of the lymph node ratio (LNR) on survival in the patients with stage III rectal cancer. Methods: We retrospectively reviewed the data of 431 consecutive patients who underwent total mesorectal excision and postoperative chemoradiotherapy for rectal cancer from 1996 to 2006. Among these patients, 232 had positive lymph nodes (LN) and constituted this analysis. The patients were divided into the following four groups based on quartiles of LNR value: LNR ≤ 0.1 (n=69), ≤ 0.2 (n=49), ≤ 0.4 (n=54), and more than 0.4 (n=60). The association between LNR and survival was evaluated by Kaplan-Meier method and multivariate analysis with covariates including age, gender, T, N stage, carcinoembryonic antigen (CEA) level, histologic differentiation, tumor size, type of operation, number of positive LNs, number of examined LNs, and LNR. Results: The median number of examined and positive LNs were 18, and 3. The median value LNR was 0.20 (range, 0.03–1). There was a strong correlation between the number of positive LNs and LNR (r=0.724, p<0.001). After a median follow-up of 53 months (range, 9–138 months), the actuarial overall survival (OS) and disease-free survival (DFS) at 5 years were 69% and 60%. Five-year survival rate decreased as LNR increased (LNR ≤ 0.1, 89%; LNR ≤ 0.2, 67%; LNR ≤ 0.4, 64%; and LNR > 0.4, 50%, p<0.0001), and LNR was only a significant prognostic factor on stepwise regression analysis (LNR ≤ 0.1, HR=1; LNR ≤ 0.2, HR=1.5, p=0.392; LNR ≤ 0.4, HR=3.0, p=0.018;LNR > 0.4, HR=4.1, p=0.003). In each subgroup of N1 and N2, the prognostic impact on OS of LNR remained (p=0.0323 in N1; p=0.0344 in N2). Conclusions: LNR was the most significant predictors of survival in the patients with stage III rectal cancer who had undergone postoperative chemoratiation. No significant financial relationships to disclose.