SWOG-S9635 Fluorouracil Plus Ethynyluracil in Advanced Colorectal Cancer Not Responded to Fluorouracil

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Ethynyluracil may help fluorouracil kill more cancer cells by making tumor cells more sensitive to the drug. PURPOSE: Phase II trial to study the effectiveness of fluorouracil plus ethynyluracil in treating patients with advanced colorectal cancer that has not responded to fluorouracil.

OBJECTIVES: I. Assess the confirmed response rate to fluorouracil (5-FU) plus ethynyluracil (776C85) in patients with metastatic colorectal cancer that has been demonstrated to be resistant to 5-FU. II. Assess time to progression and survival in this group of patients. III. Assess the frequency and severity of toxicities associated with this treatment. OUTLINE: Patients are stratified according to relapse while receiving adjuvant therapy (relapse within 12 months of completing adjuvant therapy vs relapse while receiving adjuvant therapy). Patients receive oral doses of ethynyluracil (776C85) and fluorouracil twice daily for 28 days followed by 1 week of rest. Treatment continues every 5 weeks in the absence of disease progression or unacceptable toxicity. Patients are followed every 3 months the first year, every 4 months the second year, and every 6 months thereafter. PROJECTED ACCRUAL: A total of 35-75 patients will be accrued for this study.