The Canadian Study of Diet, Lifestyle, and Health: Design and characteristics of a new cohort study of cancer risk

Background: We have established a new cohort study, the Canadian Study of Diet, Lifestyle, and Health, to investigate the relationship between diet, lifestyle factors, molecular markers, and cancer incidence in Canada. Methods: The cohort was established predominantly by recruiting alumni from the Universities of Alberta, Toronto, and Western Ontario between 1995 and 1998, but also includes a small contingent recruited mostly in 1992 through the Canadian Cancer Society. Participants completed baseline lifestyle and food frequency questionnaires, measured waist and hip circumferences, and provided hair and toenail specimens. Results: Seventy-three thousand nine hundred and nine individuals (34,291 males and 39,618 females) were recruited, with representation from all Canadian provinces and territories; 97% provided biological specimens. The mean (S.D.) ages of the male and female participants at recruitment were 51.6 (15.6) and 46.1 (15.2) years, respectively. Data from a random sample of the study subjects at baseline show that approximately one-half of the males and one-third of the females were overweight (BMI ≥ 25 kg/m2), and approximately one-quarter of all participants reported that they walked at least 4 h/week. Mean (S.D.) daily caloric intake was 2341 (697) kcal for males and 2091 (612) kcal for females. Conclusions: Given the rich repository of questionnaire and biological data, and an average follow-up time for cohort members of 10.4 years, the study is poised to make a major Canadian contribution towards understanding the roles of diet, lifestyle factors, and molecular markers in influencing cancer risk.