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

* Histologically or cytologically proven metastatic colorectal cancer * Prior surgery required * No prior treatment for metastatic disease * Disease progression while on fluorouracil adjuvant therapy * Bidimensionally measurable disease * Age: Over 18 * Performance status: SWOG 0-2 * Hematopoietic: Platelet count at least 100,000/mm3, Absolute granulocyte count at least 1,500/mm3 * Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT or SGPT no greater than 3 times ULN (no greater than 5 times ULN if liver involvement) * Renal: Creatinine clearance at least 50 mL/min * Other: Must be able to swallow and retain oral medications No nutritional support by gastrostomy feeding tube or parenteral support No intractable vomiting or nausea * Patients with history of prior malignancy must be currently disease free and off all therapy for that malignancy * Not pregnant or nursing Fertile patients must use effective contraception * Biologic therapy: No concurrent immunotherapy Chemotherapy; At least 3 weeks since prior chemotherapy and recovered; No concurrent flucytosine; No other concurrent chemotherapy * Endocrine therapy: No concurrent hormonal therapy * Radiotherapy: Prior adjuvant pelvic radiation or radiation to one area of recurrence allowed At least 4 weeks since prior radiotherapy and recovered Total area of bone marrow irradiation must not exceed 25% No concurrent radiotherapy * Surgery: At least 2 weeks since prior surgery for colorectal cancer and recovered No prior resection of the stomach or small intestine * Other: No other concurrent anticancer therapy