Microscopic resection margins adversely influence survival rates after surgery for colorectal liver metastases: An open ambidirectional Cohort Study

Background: Liver resection is the most effective treatment for patients with colorectal liver metastases (CRLMs). Patients with tumour at the resection margin (R1) are reported to have worse survival compared to those with an uninvolved resection margin (R0). Recent data has questioned this finding. This study investigates whether R1 resections adversely influence survival when compared to R0 resections. Material and methods: Patients undergoing surgery for CRLM, identified from a prospectively maintained database, from January 2007 to January 2017, were included. Univariate and multivariate survival analyses were performed. p < 0.05 was significant. Results: 282 patients were included. Median age 72 (32-90) years. 236 patients (83.7%) had chemotherapy and surgery, whilst 46 (16.3%) had surgery alone. 149 patients (52.8%) were alive at the end of the study period. R1 resection on univariate survival analysis was associated with better survival (HR 2.12, 95%CI 1.60-4.61, p = 0.0002). Multivariate analysis controlling for age and gender, identified presence of extrahepatic disease (HR 2.03, 95%CI 1.17-3.52, p < 0.001), R0 resection (HR 0.33, 95%CI 0.19-0.59, p = 0.003), primary tumour stage (HR 1.57, 95%CI 1.04-2.40, p = 0.034) and primary tumour differentiation (HR 2.56, 95%CI 1.01-6.46, p = 0.047), as prognostic factors for poorer survival. Five-year and 10-year survival were 54.3% and 41.7% respectively in patients with an R0 resection and, 25.8% and 17.2% in those with an R1 resection. Conclusion: The presence of extrahepatic disease, an R1 resection margin, advanced T-stage and poorer tumour differentiation were associated with worse survival in CRLM surgery and R0 resection is recommended.