Dietary trial in prostate cancer: Early experience and implications for clinical trial design

Much epidemiologic and case-controlled evidence suggests that diet may be a modifier of prostate cancer risk. However? the role of dietary modificatio n in men known to have prostate cancer is a matter of some debate, To eluci date the effect of diet and comprehensive lifestyle changes on cancer risk, we are conducting a randomized, prospective clinical trial on men with cli nically localized prostate cancer who have selected "watchful waiting" as p rimary therapy. Since its inception in April 1997, 93 men have been randomi zed to control (n = 47) or dietary and lifestyle intervention (n = 46). Pat ients in the intervention group are asked to eat a low-fat, soy-supplemente d vegan diet and take part in stress management, psychosocial group support , and exercise programs. After 1 year, adherence to all four interventions was greater than 80%, and no deaths or adverse outcomes have occurred. To d ate, we have collected prostate-specific antigen and endorectal magnetic re sonance imaging and spectroscopy data on 63 patients (34 control and 29 int ervention). This study demonstrates that a randomized, prospective dietary trial for men with localized prostate cancer is safe and feasible. The meth odologies used provide insights into practical aspects of diet design and c ompliance assessment that may be useful templates for future dietary trials .