Thymidylate synthase and thymidine phosphorylase expression in resected colorectal liver metastases do not predict overall survival nor response to chemotherapy

3605 Background: Enzyme expression has been reported to be of both predictive and prognostic significance in patients with colorectal liver metastases (CLM). We determined whether thymidylate synthase (TS) and/or thymidine phosphorylase (TP) can be used to determine the prognosis of patients with CLM who have undergone potentially curative hepatic resection and whether TS and/or TP status can be used to predict which patients would be likely to benefit from (neo)adjuvant chemotherapy. Methods: Paraffin tumor blocks from 99 patients who received potentially curative liver resections for CLM were evaluated. TS and TP expression were assessed by immunohistochemistry (IHC) assays. Overall survival (OS) and disease-free survival (DFS) were compared between high and low expressors of TS and TP singly and in combination. The predictive value for response to (neo)adjuvant chemotherapy of TS alone as well as the TS / TP combination were evaluated. Results: Median OS for the TS+ group (n=47) was 4.51 years and DFS ...