Physician's Health Study (PHS). Homo sapiens

This study was included as part of a GWAS consortium. The Physician's Health Study (PHS) was initiated in 1982 with 22,071 healthy U.S. male physicians, between 40 and 84 years of age who took part of a randomized, double-blind, placebo-controlled trial of aspirin and Bcarotene. Participants completed two initial questionnaires and numerous follow up questionnaires. Blood samples were collected during the first two years of the trial before randomization. Colorectal cancer cases were collected up through 2008 and matched controls were identified. Samples were genotyped in two different batches for this project due to DNA availability; the same platform and genotyping center were utilized for both sets.