The volume-time index (VTI) is prognostic in patients with colorectal cancer peritoneal metastases undergoing cytoreductive surgery and intraperitoneal chemotherapy

Peritoneal cancer index (PCI) is an important prognostic factor in colorectal cancer peritoneal metastases (CRPM), however it fails to consider the time period over which disease burden develops. The volume-time index (VTI) is the ratio between PCI and time from primary tumour resection. A retrospective cohort study of 182 patients managed from 1996 to 2017 was performed. As stratified by high vs low VTI groups, median overall survival (OS) was 23 months (95% 17–46) vs 44 months (95% 35–72) with a difference in 5-year OS of 20.3% (95%CI 10.2–40.4) vs 40.1% (95%CI 29.7–54.1), p = 0.002. No difference in 5-year recurrence free survival (RFS) exists. On multivariable analysis, an elevated VTI was independently associated with poorer OS (adjusted HR 3.20, 95%CI 1.64–6.23, p