The aim of this study was to investigate the impact of
adjuvant chemotherapy on survival of patients who had curative resection for stage IV
colorectal cancer.The efficacy of
adjuvant chemotherapy after curative resection for stage IV
colorectal cancer remains unclear.The database of 3695 patients with stage IV
colorectal cancer between 1991 and 2007 collected from 16 member hospitals of the Japanese Society for
Cancer of the Colon and Rectum was used for this investigation. The survivals of patients with and without
adjuvant chemotherapy after curative resection for stage IV
colorectal cancer were evaluated using a propensity score matching method.The data of 689 patients who underwent curative resection for both primary and synchronous metastatic
tumors were extracted from the database and used for analysis in this study. The 5-year overall survival rates of the patients with and without
adjuvant chemotherapy were 41.8% and 33.9%, respectively. A Cox proportional hazards model showed that
adjuvant chemotherapy (P = 0.0042), regional
lymph node metastasis (P < 0.0001), and peritoneal
metastasis (P = 0.0006) were independent factors for overall survival. In the propensity score-matched cohort, patients with
adjuvant chemotherapy had better overall survival than those without (P = 0.026).The present study demonstrated that
adjuvant chemotherapy improved overall survival after curative resection for stage IV
colorectal cancer. The efficacy of each chemotherapeutic regimen in the adjuvant setting for stage IV
colorectal cancer should be clarified in the future.