Thymidylate synthase: a predictive biomarker in resected colorectal liver metastases receiving 5-FU treatment.

Aim: To investigate the role of thymidylate synthase (TS) as a predictive biomarker in patients with resected colorectal liver metastases (CRLM). Materials & methods: PubMed, EMBASE and Cochrane Library were queried up to June 2017. Meta-analysis was performed using random-effects model. Risk of bias was assessed using funnel plots. Results: Six eligible studies were included, comprising a total of 542 patients. Meta-analysis demonstrated a trend to reduced overall survival in patients with resected CRLM with TS overexpression, with a hazard ratio of 1.13 (95% CI: 0.99-1.29; p = 0.08). In three studies where patients received systemic fluorouracil, the pooled hazard ratio was 2.25 (95% CI: 1.37-3.71; p = 0.001). Conclusion: TS appears to be a clinically relevant predictive biomarker in patients with resected CRLM receiving systemic 5-FU.