Simultaneous versus staged resection for synchronous colorectal cancer liver metastases: A population-based cohort study.

665Background: While considered safe, simultaneous resection of colorectal cancer primary and liver metastases is not performed routinely. We aimed to identify practice patterns, short and long-term outcomes of simultaneous vs. staged resections for synchronous colorectal cancer liver metastases. Methods: We conducted a population-based cohort study of patients undergoing resection for synchronous colorectal cancer liver metastases from 2006-2015 by linking administrative healthcare datasets in Ontario, Canada. Resection of the primary colorectal cancer and liver metastases within six months was considered synchronous disease. Simultaneous (same hospital admission) and staged resections were compared. Outcomes were 90-day post-operative mortality, total length of hospital stay, overall survival and healthcare costs. Survival for the staged group was measured from the last surgical resection to death and estimated using Kaplan Meier. Cost analysis was undertaken from the perspective of a third-party payer ...