A study of diet and breast cancer prevention in Canada: why healthy women participate in controlled trials.

Little research has been undertaken to determine why healthy people agree to enroll in randomized controlled trials of cancer prevention. This study describes the beliefs of Canadian women participating in a trial designed to determine the effect of reducing dietary fat on the development of breast cancer. Healthier eating, nutritional counseling, contributing to science, and helping others were the most frequently cited advantages of participation. Weight control and general better health were specifically associated with the dietary regimens. Attending appointments and difficulties when eating out were the main disadvantages of participation. Suggestions that would promote adherence to the trial protocol also were elicited. Responses cited most often included opportunities to meet other participants, more nutritional counseling (particularly psychological tips), updates about the trial, and more recipes. Attention should be paid to these suggestions as they characterize some of the major determinants of adherence behavior.