Impact of extent of disease on 1-year healthcare costs in patients who undergo cytoreductive surgery with hyperthermic intraperitoneal chemotherapy for colorectal peritoneal metastases: retrospective observational cohort study.

Background: The goal of this retrospective observational study was to determine the impact of the extent of peritoneal disease on 1-year healthcare costs in patients with colorectal peritoneal metastases (PM) who undergo cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS + HIPEC). The extent of peritoneal disease, expressed by the Peritoneal Cancer Index (PCI), directly affects the complexity of CRS + HIPEC and ultimately survival outcomes. The impact of the PCI on treatment-related healthcare costs remains unknown.

Methods: Data from patients with colorectal PM who underwent CRS + HIPEC between January 2012 and November 2017 were extracted retrospectively from an institutional database. Patients were divided into four subgroups with PCI scores ranging from 0 to 20. Treatment-related costs up to 1 year after CRS + HIPEC were obtained from the financial department. Differences in costs and survival outcomes were compared using the χ test and Kruskal-Wallis H test.

Results: Seventy-three patients were included (PCI 0-5, 22 patients; PCI 6-10, 19 patients; PCI 11-15, 17 patients; PCI 16-20, 15 patients). Median (i.q.r.) costs were significantly increased for the PCI 11-15 and PCI 16-20 groups (€51 029 (42 500-58 575) and €46 548 (35 194-60 533) respectively) compared with those for the PCI 0-5 and PCI 6-10 groups (€33 856 (25 293-42 235) and €39 013 (30 519-51 334) respectively) (P = 0·009).

Conclusion: Treatment-related healthcare costs are significantly increased among patients with extensive tumour burden (PCI score 10 or above) who undergo CRS + HIPEC for the treatment of colorectal PM.