Prognostic impact of tumour biology compared to surgical margin clearance for colorectal liver metastases in the era of modern chemotherapy and surgery

Abstract

Background: Historically, microscopically incomplete R1 resections have been associated with increased recurrence and lower survival rates for colorectal liver metastases (CLMs). With advances in chemotherapy, there is a shift towards a more aggressive surgical approach towards liver resection for CLMs. Recent studies have questioned the prognostic significance of obtaining complete surgical margin clearance. This study aims to compare R0 and R1 resections on oncologic outcomes. Methods: From January 2001 to December 2016, all patients who had liver resection for CLM at Singapore General Hospital were analysed retrospectively. Patients with extrahepatic metastases, macroscopic residual tumour and staged liver resections were excluded. Results: Of the 290 patients analysed, 228 (78.6%) and 62 (21.4%) patients underwent R0 and R1 resection respectively. R1 resections were associated with bilobar, multiple and synchronous liver metastases, major liver resections and adjuvant chemotherapy. Independent factors of poor overall and recurrence free-survival were primary colorectal tumour grade, presence of perineural invasion, nodal status, carcinoembryonic antigen (CEA) levels, number and size of liver metastases. R1 resection was likely associated with local intrahepatic recurrence. (HR: 0.74, 95% CI = 0.5 - 1.09, p = 0.122) However, on multivariate survival analysis, it was not an independent predictor for overall and recurrence free survival. Conclusion: Underlying tumour biology is a strong predictor of oncologic outcomes. The prognostic impact of R1 resection should be reviewed given that survival is similar to R0 resection in this current era of chemotherapy.