PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-1 Life expectancy: At least 6 months Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 125,000/mm3 Hematocrit at least 33% Hepatic: AST, LDH, alkaline phosphatase and bilirubin no greater than 2 times upper limit of normal Renal: Creatinine no greater than 1.8 mg/dL BUN no greater than 33 mg/dL Cardiovascular: No congestive heart failure (New York Heart Association class III or IV heart disease) Neurologic: No prior CNS demyelinating or inflammatory disease No prior hereditary or acquired peripheral neuropathy No organic brain syndrome, significant impairment of cognitive function, or psychiatric disorder that would preclude study Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 18 months after study No hypersensitivity to interferon alfa or any component of the injection No history of diabetes mellitus prone to ketoacidosis No uncontrolled thyroid abnormalities No clinically significant retinal abnormalities No other significant medical or surgical condition that would preclude study No prior invasive melanoma No other prior or concurrent malignancies within the past 5 years except any in situ cancer, atypical melanocytic hyperplasia, or basal or squamous skin cancer No autoimmune disorders or immunosuppressive conditions