Safety of secondary CRS/HIPEC in peritoneal surface malignancies: Insights from a national cohort study

BACKGROUND: For carefully selected patients with peritoneal surface malignancies (PSMs), secondary cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) can provide similar oncological results as primary CRS/HIPEC. However, the mortality rate and the incidence of reoperations due to perioperative complications after secondary CRS/HIPEC remain understudied. METHODS: A retrospective analysis was conducted using the StuDoQ|HIPEC registry, a prospectively maintained national German CRS/HIPEC database, to compare reoperation rates and 30-day mortality between patients undergoing primary and secondary CRS/HIPEC. The analysis included patients treated at 83 centers between 2011 and 2024. Propensity-score matching was performed to adjust for confounding factors prior to comparing outcomes between the matched cohorts. RESULTS: A comprehensive analysis of 5011 primary CRS/HIPEC cases and 236 secondary CRS/HIPEC cases showed no significant differences in reoperation rates (15 % vs. 12 %, p = 0.192) or 30-day mortality (2 % vs. 1 %, p = 0.240). After propensity-score matching to control for confounding factors, outcomes remained comparable, with identical reoperation rates of 12 % in both groups (p = 1.000) and similar 30-day mortality (2 % vs. 1 %, p = 0.685). Within the secondary CRS/HIPEC group, the male-to-female ratio was 1:3, and the median age was 55 years. The majority of these patients underwent secondary CRS/HIPEC primarily for appendiceal cancer (27 %), pseudomyxoma peritonei (21 %), or colorectal cancer (20 %), mesothelioma (12 %) and ovarian cancer (10 %). CONCLUSIONS: Secondary CRS/HIPEC can be performed safely in selected patients with PSMs, comparable to primary CRS/HIPEC. Reoperation rates and 30-day mortality rates were similar between groups, even after adjusting for confounding factors.