[Significance of tissue PyNPase, TS, and DPD activities in breast cancer]

We analyzed the interim results of prognostic significance of pyrimidine nucleoside phosphorylase (PyNPase), thymidylate synthase (TS), and dihydropyrimidine dehydrogenase (DPD) in 5-FU-based chemotherapy for breast cancer. In surgical specimens of tumor tissues and normal mammary gland tissues from 102 breast cancer patients, TS, PyNPase, and DPD activities were measured, and p53 and c-erbB-2 overexpression were also examined. TS, d-Thd-Pase/Urd-Pase (PyNPase), and DPD activities were significantly higher in tumor tissues than in normal tissues. There was a strong correlation between d-Thd-Pase and Urd-Pase in tumor tissues. No relationship was found between patient characteristics and any of the enzyme activities. PyNPase activities were significantly higher in the tissues having a c-erbB-2 overexpression of 75% (4+) or more than in those having less than 75%, and the tissues with a p53 of 50% (3+) or more had significantly higher TS activities than those with less than 50%. However, the other parameters showed no significant difference. The data obtained so far suggest no clear correlation between the activity of any of these enzymes and prognosis.