Comparison of Cytoreductive Surgery and Resection of Isolated Peritoneal Metastases in Patients with Peritoneal Metastases from Colorectal Cancer: A Retrospective Study

OBJECTIVES: This study aimed to compare the short and long-term outcomes of cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy and resection of isolated peritoneal metastases in patients with peritoneal metastases from colorectal cancer in Japan. METHODS: We included patients who had undergone surgery for peritoneal metastases from colorectal cancer between 2013 and 2019. Data were retrieved from a prospectively maintained multi-institutional database and retrospective chart review. Patients were classified into cytoreductive surgery and resection of isolated peritoneal metastases groups based on the surgery they had undergone. RESULTS: A total of 413 patients were eligible for analysis (257 and 156 patients in the cytoreductive surgery and resection of isolated peritoneal metastases groups, respectively). There was no significant difference in overall survival (hazard ratio and 95% confidence intervals, 1.27 [0.81, 2.00]). Six cases (2.3%) of postoperative mortality were observed in the cytoreductive surgery group, whereas none were observed in the resection of the isolated peritoneal metastases group. Cases of postoperative complications were significantly higher in the cytoreductive surgery group (risk ratio 2.02 [1.18, 2.48]) than those in the resection of isolated peritoneal metastases group. Among patients with a high peritoneal cancer index (6 points or higher), the complete resection rate was 115/157 (73%) and 15/44 (34%) in the cytoreductive surgery and the resection of isolated peritoneal metastases groups, respectively. CONCLUSIONS: Cytoreductive surgery was not superior in providing long-term survival benefits for colorectal cancer peritoneal metastases; however, cytoreductive surgery provided a higher complete resection rate even in patients with a high peritoneal cancer index (6 points or higher).