This is a prospective cohort study of diet and cancer in relation to several major cancers, especially breast, prostate, and colorectal malignancies. The cohort comprises 50-69 year-old male and female members of the American Association of Retired Persons (AARP). In 1995-6 we mailed baseline questionnaires to 3.5 million AARP members. Over 615,000 AARP members responded, with over 540,000 providing adequate dietary data. Preliminary analysis indicates that the cohort, both men and women, has the desired wide distributions of percent calories from fat, dietary fiber, fruits and vegetables, and red meat. Approximately 330,000 of the initial respondents (with satisfactory data) returned a second questionnaire containing questions on exposures not assessed in the first instrument.

In terms of field activities, the study has been relatively quiescent over the past year. At the end of the five-year period of observation, we will mail to cohort members a brief follow-up questionnaire primarily targeted to endpoint assessment. (Because of cancer registry lag-time, we do not expect to mail this questionnaire until early 2002.) Follow-up will be largely passive, through established state registries. The initial questionnaire mailing will be to AARP members in those states selected on the basis of having registries with adequate coverage and quality. We will use active follow-up, with record retrieval, for the small percentage of cohort members who have moved out of the cancer registry areas. The buccal cell collection pilot study has been completed; over 50% of those pilot study partricipants who had completed the baseline and risk factor questionnaires returned buccal cell speciments. Preliminary data from a pilot study of the end point ascertainment procedure indicate that cohort incidence rates for major cancers, determined from registry data, are consistent with SEER rates.