During follow-up visits, participants will be asked whether they experienced any medical events since the last study visit, with information on specific diagnoses including prostate cancer, lung cancer, colon cancer, other cancers, stroke, myocardial infarction, hypertension, diabetes mellitus, kidney disease, chronic prostatitis, and benign prostatic hypertrophy. Confirmation of self-reported diagnosis will be made by an examination of discharge summaries, medical records, and available diagnostic and laboratory information by an end-points committee.