PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent biologic therapy Chemotherapy: No concurrent chemotherapy Endocrine therapy: No concurrent endocrine therapy Radiotherapy: No concurrent radiotherapy Surgery: Prior surgical ablation of prior dysplastic sites allowed Other: At least 2 months since prior therapy toxicities Patient Characteristics-- Age: Not specified Performance Status: SWOG 0-1 Life Expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception at least 1 month before, during, and at least 2 months after study