Risk factors for complications after cytoreductive surgery (CRS) and HIPEC in 290 peritoneal malignancies of primary and secondary origins.

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is effective for selected peritoneal malignancies but carries potential postoperative morbidity. Defining complication rates, severity and predictors is crucial to optimize management, patient selection, and risk stratification. A retrospective observational study was conducted including patients with primary or secondary peritoneal surface malignancies who underwent CRS-HIPEC between 2002 and 2025. Postoperative complications were graded according to CTCAE and Clavien-Dindo classifications. Early postoperative renal function was evaluated in a select cohort receiving sodium thiosulfate nephroprotection. A total of 290 patients were included (median age 60 years, PCI 5). Standard-extended peritonectomy was performed in 167 (57.6%) cases, and multivisceral resection in 27 (10.7%). Optimal debulking was achieved in 263 (90.7%). Postoperative complications occurred in 51.7%, medical and chemotherapy-related complications in 45.5% and surgical ones in 12.4% of cases. Postoperative anemia was common (32.7%), predominantly at CTCAE Grade 3. Severe complications, graded as 3-5 according to ClavienDindo score, occurred in 11.7%, mainly in elderly (20.4% vs. 9.7%, p = 0.090), with no 30-day mortality. Older age, higher comorbidity burden and splenectomy emerged as predictors of severe complications. In 22 patients receiving sodium thiosulfate, creatinine and urine output were significantly lower on postoperative day 5-7, suggesting a renal protective effect. Overall, 3-year survival was 62.2%. Anastomotic fistula (HR 2.43, p = 0.015), surgical site infection (1.81, p = 0.070), and thrombocytopenia (3.64, p < 0.001) were independent negative prognostic factors. CRS and HIPEC can be performed with acceptable morbidity and low mortality in specialized center. Further efforts to reduce complications are essential to improve postoperative outcomes and overall prognosis.