ASO Visual Abstract: Survival Outcomes of Optimally Treated Colorectal Metastases–The Importance of R0 Status in Surgical Treatment of Hepatic and Peritoneal Surface Disease

Background Although colorectal hepatic metastases (HM) and peritoneal surface disease (PSD) are distinct biologic diseases, they may have similar long-term survival when optimally treated with surgery. Methods This study retrospectively reviewed prospectively managed databases. Patients undergoing R0 or R1 resections were analyzed with descriptive statistics, the Kaplan–Meier method, and Cox regression. Survival was compared over time for the following periods: 1993–2006, 2007–2012, and 2013–2020. Results The study enrolled 783 HM patients undergoing liver resection and 204 PSD patients undergoing cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). Compared with PSD patients, HM patients more often had R0 resections (90.3% vs. 32.4%), less often had pre-procedure chemotherapy (52.4% vs. 92.1%), and less often were functionally independent (79.7% vs. 95.6%). The 5-year overall survival for HM was 40.9%, with a median survival period of 45.8 months versus 25.8% and 33.4 months, respectively, for PSD ( p < 0.05). When stratified by resection status, R0 HM and R0 PSD did not differ significantly in median survival (49.0 vs. 45.4 months; p = 0.83). The median survival after R1 resection also was similar between HM and PSD (32.6 vs. 26.9 months; p = 0.59). Survival between the two groups again was similar over time when stratified by resection status. The predictors of survival for HM patients were R0 resection, number of lesions, intraoperative transfusion, age, and adjuvant chemotherapy. For the PSD patients, the predictors were peritoneal cancer index (PCI) score, estimated blood loss (EBL), and female gender. Conclusion The study showed that R0 resections are associated with improved outcomes and that median survival is similar between HM and PSD patients when it is achieved. Surveillance and treatment strategies that facilitate R0 resections are needed to improve results, particularly for PSD.