PRIOR CONCURRENT THERAPY: Biologic therapy: Prior biologic therapy (interleukin-2, interferon, monoclonal antibodies, and/or retinoids) permitted Recovered from prior biologic therapy Chemotherapy: No more than one prior chemotherapy regimen for advanced or relapsed disease No chemotherapy within 4 weeks prior to study Prior neoadjuvant or radiosensitizing chemotherapy allowed Endocrine therapy: Not specified Radiotherapy: Prior radiotherapy permitted Recovered from prior radiotherapy Surgery: Recovered from major surgery