PRIOR CONCURRENT THERAPY: Biologic therapy: Prior biological therapy allowed Chemotherapy: Prior systemic chemotherapy allowed Patients with more than 1 prior regimen analyzed separately At least 4 weeks since chemotherapy (6 weeks since nitrosoureas or mitomycin) Endocrine therapy: Not specified Radiotherapy: Prior skin irradiation allowed At least 4 weeks since wide-field radiotherapy Surgery: Fully recovered from prior surgery Other: Prior topical therapy allowed Prior PUVA allowed