3. Patients with prior malignancies are eligible if they have been disease-free for > 5 years and are deemed by their physician to be at low risk for recurrence. Patients with squamous or basal cell carcinoma of the skin, melanoma in situ, carcinoma in situ of the cervix, or carcinoma in situ of the colon or rectum that have been effectively treated are eligible, even if these conditions were diagnosed within 5 years prior to randomization.