Comparison of EPIC Versus HIPEC in the Treatment of Colorectal Peritoneal Metastases and Appendix Tumors Using Inverse Probability of Treatment Weighting

Background: The selection of hyperthermic intraperitoneal chemotherapy (HIPEC) or early postoperative intraperitoneal chemotherapy (EPIC) for peritoneal metastases from colorectal cancer or appendiceal neoplasms following cytoreductive surgery (CRS) depends on the surgeon’s discretion. This study was designed to compare postoperative and oncologic outcomes of HIPEC and EPIC using inverse probability of treatment weighting (IPTW). Methods: This study included 175 patients who received HIPEC or EPIC following CRS at a single tertiary university hospital between December 1999 and December 2020. Inverse probability of treatment weighting analysis was performed to control for pretreatment characteristics between the two groups. Multivariate analysis was performed to determine factors associated with postoperative and survival outcomes. Results: After IPTW, no significant differences in baseline demographics and tumor characteristics were observed between the two groups. The HIPEC group had a significantly longer operation time than the EPIC group. The EPIC group showed a significantly higher postoperative mortality rate than the HIPEC group. Operation time (odds ratio [OR] 1.01; 95% confidence interval [CI] 1.01–1.02; p < 0.001), bowel anastomosis (OR 7.25; 95% CI 1.16–45.2; p = 0.034), neoadjuvant chemotherapy (OR 7.62; 95% CI 1.85–31.4; p = 0.005), and EPIC (OR 8.76; 95% CI 2.16–35.5; p = 0.002) were independent risk factors for major surgical complications. No association was observed between intraperitoneal chemotherapy type and major hematologic toxicity, overall survival, progression-free survival, or peritoneal progression-free survival. Conclusions: EPIC was a risk factor for major surgical complications. Survival outcomes were similar between the two types of intraperitoneal chemotherapy.