Topoisomerase-I, thymidylate synthase primary tumour expression and clinical efficacy of 5-FU/CPT-11 chemotherapy in advanced colorectal cancer patients

While several studies have reported that thymidylate synthase (TS) tumour expression can be a reliable predictive marker of clinical response to 5-Fluorouracil (5-FU) for advanced colorectal cancer patients, only a few studies that searched for predictive factors of irinotecan (CPT-11) clinical response are available. The aim of the present study has been to verify the predictive value of immunohistochemical topoisomerase-I (Topo-I) and TS primary tumour expression in a consecutive series of 62 advanced colorectal cancer patients that received a first line 5-FU/CPT-11 chemotherapy. TS and Topo-I immunostaining was observed in 76% and 43% of tumours, respectively, resulting in a significant relationship within each tumour (r=0.365, p