Evaluating long-term outcomes after cytoreductive surgery for colorectal peritoneal metastasis: do long survivors really exist?

Abstract

Background: Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has demonstrated improved overall survival (OS) and disease-free survival (DFS) in carefully selected patients with peritoneal metastases from colorectal cancer (CRC-PM). The primary aim of this retrospective study was to identify patients treated with CRS + HIPEC who achieved long-term survival and to analyze the factors most strongly associated with prolonged survival. Methods: Among those eligible for CRS + HIPEC, a group of patients with adequate follow-up was evaluated and divided into two groups: the long-term survival group (OS > 48 months) and the average-term survival group (OS < 48 months). A comparative analysis was performed between the two groups to evaluate which factors might be associated with an increased likelihood of long-term survival. Propensity score matching (PSM) was employed to homogenize patients based on peritoneal cancer index (PCI) and extensive small bowel involvement. A further analysis was conducted to assess the differences in recurrence behavior between the two groups. Results: During the study period, 116 patients underwent CRS + HIPEC. The median OS for the entire sample was 52 months. Among the 63 patients with at least 4 years of follow-up, 32 were identified as part of the average survival group (AS-G), while 31 were classified in the long-survival group (LS-G). DFS and survival after recurrence were statistically higher in the LS-G compared to the AS-G. Higher PCI, BRAF V600E mutation, right-sided primary tumor location, small bowel involvement, and mucinous histology were statistically more frequent in the AS-G compared to the LS-G. After PSM analysis, the absence of BRAF V600E mutation and the non-mucinous histology were significantly associated with long-term survival. Conclusions: Long-term survival can potentially be achieved in patients with peritoneal metastasis from colorectal cancer (CRC) treated with CRS and HIPEC, often resulting in prolonged disease-free periods and less aggressive disease progression if recurrence occurs.