Fluorouracil-Uracil and Leucovorin in Treating Elderly Patients With Metastatic Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically confirmed metastatic colorectal adenocarcinoma Measurable disease PATIENT CHARACTERISTICS: Age: 75 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL AST or ALT no greater than 2.5 times upper limit of normal (ULN) Renal: Creatinine no greater than 1.5 times ULN Other: No serious infection No other serious underlying medical condition that would preclude protocol therapy No known hypersensitivity to fluorouracil-uracil or leucovorin calcium PRIOR CONCURRENT THERAPY: Biologic therapy: At least 6 months since prior adjuvant immunotherapy for colorectal cancer No concurrent immunotherapy Chemotherapy: At least 6 months since prior adjuvant chemotherapy for colorectal cancer No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy Radiotherapy: See Disease Characteristics At least 6 months since prior adjuvant radiotherapy for colorectal cancer Prior radiotherapy for locally symptomatic disease allowed Surgery: Prior surgery allowed Other: No prior therapy for metastatic disease No other concurrent investigational drugs No concurrent halogenated antiviral agents (e.g., lodenosine, fialuridine, FMAU, emtricitabine, and sorivudine)