S9716: Combination Chemotherapy in Treating Patients With Merkel Cell Cancer

DISEASE CHARACTERISTICS: Histologically proven unresectable Merkel cell carcinoma Local-regional OR Metastatic Bidimensionally measurable disease If all known sites previously irradiated, disease must be progressive CNS metastases allowed if not only site of measurable disease No pleural effusions or ascites PATIENT CHARACTERISTICS: Age: 18 and over Performance status: SWOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1500/mm3 Platelet count at least 100,000/mm3 Hepatic: Not specified Renal: Not specified Other: Not pregnant or nursing Fertile patients must use effective contraception No other prior malignancy within 5 years except: Adequately treated basal cell or squamous cell skin cancer Adequately treated stage I or II cancer In situ cervical cancer PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic therapy or immunotherapy No concurrent immunotherapy Chemotherapy: No prior chemotherapy for metastatic disease At least 4 weeks since prior adjuvant chemotherapy No prior adjuvant cyclophosphamide, methotrexate, or fluorouracil No other concurrent chemotherapy Endocrine therapy: No concurrent hormone therapy Radiotherapy: See Disease Characteristics At least 14 days since prior radiotherapy Surgery: At least 2 weeks since prior surgery