PRIOR CONCURRENT THERAPY: Recovered from toxic effects of prior treatment Biologic therapy: No immunologic therapy within the past 2 weeks Chemotherapy: No chemotherapy within the past 4 weeks (6 weeks for mitomycin or nitrosoureas) See Disease Characteristics Endocrine therapy: No hormonal therapy within the past 2 weeks See Disease Characteristics Radiotherapy: No radiotherapy within the past 4 weeks See Disease Characteristics Surgery: Not specified Other: No concurrent cholesterol lowering agents, supplemental vitamins, or other antioxidants