Impact of R0 resection for synchronous peritoneal metastasis from colorectal cancer: A propensity score‐matched analysis of a multi‐institutional database

AIM: To investigate the usefulness of resection for synchronous peritoneal metastasis from colorectal cancer. METHODS: The patients who underwent surgery for stage IV colorectal cancer at 16 hospitals between 1991 and 2007 were enrolled in this study. The overall survival rates of patients with synchronous peritoneal metastasis from colorectal cancer with and without R0 resection were compared using a propensity score‐matched analysis. RESULTS: Among the 3965 patients with stage IV colorectal cancer, 1169 had synchronous peritoneal metastasis (28.5%). No patients received hyperthermic intraperitoneal chemotherapy (HIPEC) in this study. Among the 1169 patients, 783 had enough clinicopathologic information and went through further analysis. Out of 783 patients, 204 underwent R0 resection. A multivariate analysis revealed that severity of peritoneal metastasis according to the Japanese classification (P < .0001) and distant metastases (P < .0001) were independently associated with non‐R0 resection. In a propensity score‐matched analysis, 118 patients who underwent R0 resection were matched with 118 patients who did not undergo R0 resection. There was no significant difference in each parameter between patients with and without R0 resection. After matching, the overall survival in patients with R0 resection was better than that without R0 resection (median survival time: 28.8 months and 15.6 months, P < .0001). CONCLUSION: The overall survival of patients with R0 resection for synchronous peritoneal metastasis from colorectal cancer was better than that without R0 resection even without HIPEC.