Current and Past Smoking Increases Risk for Colorectal Cancer

Setting and participants. This study examined participants in the Cancer Prevention Study II (CPS-II) Nutrition Cohort, a prospective study examining the impact of environmental and lifetyle factors on cancer incidence and mortality in 184,187 American men and women. The CPS-II Nutrition Cohort is a subgroup of the CPS-II, a prospective mortality study of 1.2 million participants established in 1982 by the American Cancer Society. Participants in the CPS-II mortality cohort residing in 21 states with state cancer registries, aged 50 to 74 years in 1992, were invited to participate in the Nutrition Cohort. Subjects completed a mailed questionnaire upon entry regarding demographic, behavioral, environmental, occupational, medical, and dietary risk factors. Two-year follow-up questionnaires were sent to cohort members in 1997, 1999, 2001, 2003, and 2005 to update exposure information and elucidate new health problems, including cancer. The response rate among living participants was at least 89% for each of the follow-up questionnaires. The follow-up period ended on 30 June 2005 for this particular analysis.