A Phase I trial of preoperative eniluracil plus 5-fluorouracil and radiation for locally advanced or unresectable adenocarcinoma of the rectum and colon.

Purpose: Eniluracil, an effective inactivator of dihydropyrimidine dehydrogenase, allows for oral dosing of 5-fluorouracil (5-FU), which avoids the morbidity of continuous infusion 5-FU. We addressed the safety of oral eniluracil and 5-FU combined with preoperative radiotherapy and determined the recommended Phase II dose and dose-limiting toxicity in patients with locally advanced rectal and colon cancer.

Methods And Materials: Patients with TNM Stage II or III rectal cancer and residual or recurrent colon cancer received eniluracil (starting at 6.