Prognostic factors associated with primary cancer in curatively resected stage IV colorectal cancer

Purpose The aim of this study is to evaluate the prognostic factors associated with primary cancer in patients with curatively resected stage IV colorectal cancer, based on lymph node status. Methods A total of 468 consecutive patients with curatively resected stage IV colorectal cancer from October 1994 to December 2010 were prospectively enrolled. Survival curves were constructed using the Kaplan-Meier method, and multivariate analysis assessed independent prognostic factors. Results During the median follow-up period of this study, which was 37 months (range 1-177), the 3- and 5-year overall survival rates were 66.5 and 52.1 %, respectively, and the 3- and 5-year disease-free survival rates were 43.0 and 38.2 %, respectively. According to multivariate analysis, adjuvant chemotherapy and the preoperative serum carcinoembryonic antigen (CEA) level were independent prognostic factors for overall survival, and primary tumor location and preoperative serum CEA level were independent variables for disease-free survival. For the patients with N0 and N1 tumors, the overall survival curves in the preoperative CEA groups differed significantly (P = 0.046 and P < 0.013, respectively). However, for patients with pN2 tumors, the overall survival did not differ significantly according to the preoperative CEA (P = 0.948). Conclusion The preoperative serum CEA level is a reliable predictor of recurrence and survival after curative surgery in patients with metastatic colorectal cancer. A multidisciplinary approach that combines both complete resection and adjuvant chemotherapy may achieve improved overall survival in these patients.