Inclusion Criteria

- 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