Blood and tissue samples are collected periodically for biomarker laboratory studies. Blood samples are analyzed for levels of prostate-specific antigen, chromogranin A, alkaline phosphatase, alpha tocopherol, lycopene, and other vitamins; levels of selenium by atomic absorption spectrometry; and oxidative damage to DNA. Tissue samples are analyzed for levels of Bcl-2, p53, Ki-67, thioredoxin reductase, thioredoxin, and glutathione peroxidase by immunohistochemistry and for apoptotic index by TUNEL assay.