Tegafur and 5-fluorouracil pelvic tissue concentrations in rectal cancer patients receiving preoperative chemoradiation.

Background and purpose To investigate the presence of 5-Fluorouracil (5-FU) in pelvic tissue after oral administration of tegafur. To measure tegafur and 5-FU concentrations in normal rectal mucosa, perirectal fat and residual tumor in rectal cancer patients receiving preoperative chemoradiation. To correlate drug concentrations with cancer down-staging effects.