Recurrence patterns following CRS-HIPEC in patients with colorectal peritoneal metastases: Insights from the Dutch CRS-HIPEC registry

Introduction: Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is currently the only treatment with curative intent for selected patients with colorectal peritoneal metastases. This population-based study determined the 3-year cumulative incidence of disease recurrence after CRS-HIPEC, identified factors associated with disease recurrence and described how recurrent disease is treated. Materials and methods: All patients who underwent complete CRS-HIPEC for non-appendiceal colorectal peritoneal metastases with or without extra-peritoneal metastases in 2019 were selected from the Dutch CRS-HIPEC registry. Follow up data were collected in 2023-2024. Three-year cumulative incidence of recurrence was calculated. Multivariable Cox competing risk regression analysis was used to identify factors associated with recurrence. Results: A total of 157 patients was analysed with a median follow-up of 31.0 (IQR 17.8-49.5) months. The 3-year cumulative incidence of disease recurrence was 86.3 %. Three-year recurrence-free and overall survival were 13.7 % and 47.8 % respectively. The most common sites of first recurrence were the peritoneum (68.2 %), liver (40.2 %) and lung (37.9 %). Treatment of recurrence was performed in 80.3 % of patients. Treatment mostly entailed systemic therapy (67.9 %). Secondary CRS-HIPEC was performed in 7.6 % of the patients. Factors associated with a higher risk of recurrence were a higher Peritoneal Cancer Index score (HR 1.06, 95 % CI 1.03-1.09) and pN2 (HR 2.07, 95 % CI 1.28-3.36). Conclusion: Most patients that underwent CRS-HIPEC for colorectal peritoneal metastases developed recurrent disease within 3 years. Future research should focus on ongoing developments in both diagnostics and treatment to prevent early recurrence.