Extent of Colorectal Peritoneal Carcinomatosis: Attempt to Define a Threshold Above Which HIPEC Does Not Offer Survival Benefit: A Comparative Study

Background: The main prognostic factors after complete cytoreductive surgery (CCRS) of colorectal peritoneal carcinomatosis (PC) followed by intraperitoneal chemotherapy (IPC) are completeness of the resection and extent of the disease. This study aimed to determine a threshold value above which CCRS plus IPC may not offer survival benefit compared with systemic chemotherapy. Methods: Between March 2000 and May 2010, 180 patients underwent surgery for PC from colorectal cancer with intended performance of CCRS plus IPC. Results: Among the 180 patients, CCRS plus IPC could be performed for 139 patients (curative group, 77 %), whereas it could not be performed for 41 patients (palliative group, 23 %). The two groups were comparable in terms of age, gender, primary tumor characteristics, and pre- and postoperative systemic chemotherapy. The mean peritoneal cancer index (PCI) was lower in the curative group (11 ± 7) than in the palliative group (23 ± 7) (p < 0.0001). After a median follow-up period of 60 months (range 47–74 months), the 3-year overall survival (OS) rate was 52 % [95 % confidence interval (CI) 43–61 %] in the curative group compared with 7 % (95 % CI 2–25 %) in the palliative group. Comparison of the survivals for each PCI (ranging from 5 to 36) shows that OS did not differ significantly between the two groups of patients when the PCI was higher than 17 (hazard ratio 0.64; range 0.38–1.09). Conclusion: This study confirmed the major prognostic impact of PC extent. When the PCI exceeds 17 in PC of colorectal origin, CCRS plus IPC does not seem to offer any survival benefit.