PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy or immunotherapy No concurrent immunotherapy Chemotherapy: No prior chemotherapy for metastatic disease At least 6 months since prior adjuvant chemotherapy, including cisplatin or gemcitabine, for radiosensitization in locally advanced disease No prior cisplatin or gemcitabine for locally advanced disease No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to 25% or more of bone marrow No concurrent radiotherapy Surgery: Not specified Other: No other concurrent investigational agents