Cytoreductive surgery of colorectal peritoneal metastases: outcomes after complete cytoreductive surgery and systemic chemotherapy only.

Background: Cytoreductive peritoneal surgery (CRS) associated with hyperthermic peritoneal chemotherapy (HIPEC) has long been considered the standard treatment for colorectal peritoneal metastases (CPM). However, although efficacy of surgery has been demonstrated, evidence supporting HIPEC's role is less certain.

Method: Overall survival (OS), progression-free survival (PFS) and morbidity were analysed retrospectively for fifty consecutively included patients treated for colorectal CPM with complete CRS and systemic chemotherapy only.

Results: Median peritoneal cancer index (PCI) was 8 (range 1-24). 23 patients had liver or lung metastases (LLM). 22 patients had synchronous CPM. 27 complications occurred (12 Grade 1/2, 14 Grade 3, 1 Grade 4a, 0 Grade 5). Median follow-up was 62.5 months (95 %CI 45.4-81.3), median survival 32.4 months (21.5-41.7). Three- and 5-year OS were 45.5% (0.31-0.59) and 29.64% (0.17-0.44) respectively. Presence of LLMs associated with peritoneal carcinomatosis was significantly associated with poorer prognosis, with survival at 5 years of 13.95% (95 %CI 2.9-33.6) vs. 43.87% (22.2-63.7) when no metastases were present (P= 0.018). Median PFS was 9.5 months (95 %CI 6.2-11.1).

Conclusion: With an equivalent PCI range and despite one of the highest rates of LLM in the literature, our survival data of CRS + systemic chemotherapy only compare well with results reported after additional HIPEC. Tolerance was better with acceptable morbidity without any mortality. Extra-hepatic metastasis (LLM) is a strong factor of poor prognosis. Awaiting the results of the randomized PRODIGE trial, these results indicate that CRS + systemic chemotherapy only is a robust hypothesis to treat colorectal CPM.