PATHOLOGIC NODAL CLASSIFICATION IS THE MOST DISCRIMINATING PROGNOSTIC FACTOR FOR DISEASE-FREE SURVIVAL IN RECTAL CANCER PATIENTS TREATED WITH PREOPERATIVE CHEMORADIOTHERAPY AND CURATIVE RESECTION

Abstract

Purpose: We retrospectively evaluated the effects of clinical and pathologic factors on disease-free survival (DFS) with the aim of identifying the most discriminating factor predicting DFS in rectal cancer patients treated with preoperative chemoradiotherapy (CRT) and curative resection. Methods and Materials: The study involved 420 patients who underwent preoperative CRT and curative resection between August 2001 and October 2006. Gender, age, distance from the anal verge, histologic type, histologic grade, pretreatment carcinoembryonic antigen (CEA) level, cT, cN, cStage, circumferential resection margin, type of surgery, preoperative chemotherapy, adjuvant chemotherapy, ypT, ypN, ypStage, and tumor regression grade (TRG) were analyzed to identify prognostic factors associated with DFS. To compare the discriminatory prognostic ability of four tumor response related pathologic factors (ypT, ypN, ypStage, and TRG), the Akaike information criteria were calculated. Results: The 5-year DFS rate was 75.4%. On univariate analysis, distance from the anal verge, histologic type, histologic grade, pretreatment CEA level, cT, circumferential resection margin, type of surgery, preoperative chemotherapeutic regimen, ypT, ypN, ypStage, and TRG were significantly associated with DFS. Multivariate analysis showed that the four parameters ypT, ypN, ypStage, and TRG were, consistently, significant prognostic factors for DFS. The ypN showed the lowest Akaike information criteria value for DFS, followed by ypStage, ypT, and TRG, in that order. Conclusion: In our study, ypT, ypN, ypStage, and TRG were important prognostic factors for DFS, and ypN was the most discriminating factor.