Survival after liver resection in metastatic colorectal cancer: review and meta-analysis of prognostic factors.

BACKGROUND: Hepatic metastases develop in approximately 50% of colorectal cancer (CRC) cases. We performed a review and meta-analysis to evaluate survival after resection of CRC liver metastases (CLMs) and estimated the summary effect for seven prognostic factors. METHODS: Studies published between 1999 and 2010, indexed on Medline, that reported survival after resection of CLMs, were reviewed. Meta-relative risks for survival by prognostic factor were calculated, stratified by study size and annual clinic volume. Cumulative meta-analysis results by annual clinic volume were plotted. RESULTS: Five- and 10-year survival ranged from 16% to 74% (median 38%) and 9% to 69% (median 26%), respectively, based on 60 studies. The overall summary median survival time was 3.6 (range: 1.7-7.3) years. Meta-relative risks (95% confidence intervals) by prognostic factor were: node positive primary, 1.6 (1.5-1.7); carcinoembryonic antigen level, 1.9 (1.1-3.2); extrahepatic disease, 1.9 (1.5-2.4); poor tumor grade, 1.9 (1.3-2.7); positive margin, 2.0 (1.7-2.5); >1 liver metastases, 1.6 (1.4-1.8); and >3 cm tumor diameter, 1.5 (1.3-1.8). Cumulative meta-analyses by annual clinic volume suggested improved survival with increasing volume. CONCLUSION: The overall median survival following CLM liver resection was 3.6 years. All seven investigated prognostic factors showed a modest but significant predictive relationship with survival, and certain prognostic factors may prove useful in determining optimal therapeutic options. Due to the increasing complexity of surgical interventions for CLM and the inclusion of patients with higher disease burdens, future studies should consider the potential for selection and referral bias on survival.