PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and recovered Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to more than 10% of bone marrow No prior electron-beam radiotherapy At least 4 weeks since other prior radiotherapy Surgery: Prior surgery allowed Other: Recovered from prior therapy