Peritoneal Metastases of Colorectal Origin Treated with Complete Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy: The Efficiency of Mitomycin C

Background Survival of patients affected by colorectal cancer peritoneal metastases (CRC-PM) can be improved with combined complete cytoreductive surgery (CCRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Two chemotherapeutic agents are mainly used: mitomycin C (MMC) and oxaliplatin. A recent prospective randomized clinical trial showed that oxaliplatin-based HIPEC does not improve survival compared with CCRS alone. The purpose of our study was to compare the survival effectiveness of MMC versus oxaliplatin-based HIPEC using a homogeneous surgical technique and drug protocol. Methods This retrospective monocentric study included all patients prospectively registered for having undergone CCRS and HIPEC using MMC or oxaliplatin for CRC-PM in Strasbourg University Hospital, France, from December 2004 until December 2019. MMC-based HIPEC and oxaliplatin-based HIPEC groups were compared with an inverse probability of treatment weighting. Results A total of 137 patients were included. Groups were comparable for all baseline characteristics except for peritoneal carcinomatosis index. In the weighted multivariate analysis, disease-free survival (DFS) and peritoneal disease-free survival (PDFS) were significantly higher in the MMC-based HIPEC group compared with the oxaliplatin-based HIPEC group with a hazard ratio of 0.74 (CI 95% 0.56-0.98), p = 0.035 and 0.59 (CI 95% 0.40-0.98), p = 0.0084, respectively. There was no difference in overall survival or postoperative morbidity between groups. Conclusions These results favor a superiority of MMC for DFS and PDFS in comparison with oxaliplatin in HIPEC after CCRS in treatment with curative intent for CRC-PM.