Predictive Value of Expression of ERCC 1 and GST-p for 5-Fluorouracil/Oxaliplatin Chemotheraphy in Advanced Colorectal Cancer

Background/Aims: The aim of this study was to determine whether expression of the excision repair cross complementing protein (ERCC1), glutathione S-transferase pi (GST-p) and thymidylate synthase (TS) predict response in patients with advanced colorectal cancer treated with 5-fluorouracil/oxaliplatin chemotherapy. Methodology: The study population consisted of 39 patients with advanced colorectal cancer (median age, 65 years). Patients were treated with the modified FOLFOX 6 regimen. The expression of ERCC-1, GST-p and TS of primary tumors were examined by immunohistochemistry. Results: The response rate of modified FOLFOX 6 chemotherapy was 51.3%. The positive rates of ERCC-1, GST-p and TS were 43.6%, 33.3% and 66.7%, respectively. The patients without ERCC-1 (p=0.0248) or GST-p (p=0.0019) expression were more likely to respond to chemotherapy. TS expression did not correlate with chemotherapeutic response. Conclusions: Immunohistochemical studies for ERCC-1 and GST-p may be useful in prediction of the response to 5-fluorouracil/oxaliplatin chemotherapy in advanced colorectal cancer patients.