Secondary cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for recurrent colorectal peritoneal metastases

Secondary treatment of recurrent colorectal peritoneal metastases after previous cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is poorly investigated. To evaluate the overall survival outcome of secondary (repeat) CRS + HIPEC compared to palliative treatment in recurrent peritoneal disease. Patients with colorectal peritoneal metastases treated with an index CRS + HIPEC and subsequently having recurrent peritoneal disease were identified from the prospective Swedish national HIPEC registry. Patients were divided into interventional group (secondary CRS + HIPEC) or palliative group. Multivariable logistic regression, propensity-score matching, and survival outcomes were calculated. Among 575 patients who underwent complete CRS between 2010 and 2021, 208 (36 %) were diagnosed with a subsequent recurrent peritoneal disease. Forty-two patients (20 %) were offered secondary CRS + HIPEC. Propensity-score matching of secondary interventional cases with palliative cases succeeded in 88 % (n = 37) in which female sex, lower peritoneal cancer index at index surgery, longer disease-free interval, and absence of extra-peritoneal metastases were identified as the most relevant matching covariates. Median OS from date of recurrence was 38 months (95%CI 30–58) in the interventional group and 19 months (95%CI: 15–24) in the palliative group (HR 0.35 95%CI: 0.20–0.63, p = 0.0004). Sensitivity analyses confirmed the results. As reference, the median OS from index CRS + HIPEC in the whole colorectal registry (n = 575) was 41 months (95%CI: 38–45). After matching for relevant factors, the hazard ratio for death was significantly reduced in patients who were offered a secondary CRS + HIPEC procedure for recurrent peritoneal disease. Selection bias is inherent, but survival outcomes were comparable to those achieved after the initial procedure.