Thymidine phosphorylase and dihydropyrimidine dehydrogenase are predictive factors of therapeutic efficacy of capecitabine monotherapy for breast cancer-preliminary results.

Capecitabine monotherapy was administered for 25 patients with advanced or recurrent breast cancer, and the clinical therapeutic efficacy and its relationship to expression of 5-fluorouracil-related enzymes (i. e., thymidine phosphorylase (TP), thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD)) were investigated. The expressions of TP, TS and DPD were determined by immunohistochemical staining techniques and rated using a scoring system of 1~4. The expression score for TP/DPD showed a statistically significant correlation with the clinical response, whereas the expression score for TP/TS also showed a correlation but it was not statistically significant. The number of patients was small, but the results revealed the potential of application of the TP/DPD expression score as a factor for predicting the efficacy of the drug in individual patients.