Prospective study of fruit and vegetable intake and risk of prostate cancer

Background Several epidemiologic studies have reported associations between fruit and vegetable intake and reduced risk of prostate cancer, but the findings are inconsistent and data on clinically relevant advanced prostate cancer are limited. Methods We evaluated the association between prostate cancer risk and intake of fruits and vegetables in 1338 patients with prostate cancer among 29361 men (average follow-up = 4.2 years) in the screening arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Participants completed both a general risk factor and a 137-item food-frequency questionnaire at baseline. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% confidence intervals (Cis). All statistical tests were two-sided. Results Vegetable and fruit consumption was not related to prostate cancer risk overall; however, risk of extra-prostatic prostate cancer (stage III or IV tumors) decreased with increasing vegetable intake (RR = 0.41, 95% Cl = 0.22 to 0.74, for high versus low intake; P-trend =.01). This association was mainly explained by intake of cruciferous vegetables (RR = 0.60, 95% Cl = 0.36 to 0.98, for high versus low intake; P-trend =.02), in particular, broccoli (RR = 0.55, 95% Cl = 0.34 to 0.89, for >1 serving per week versus <1 serving per month; P-trend =.02) and cauliflower (RR = 0.48, 95% Cl = 0.25 to 0.89 for >1 serving per week versus <1 serving per month; P-trend =.03). We found some evidence that risk of aggressive prostate cancer decreased with increasing spinach consumption, but the findings were not consistently statistically significant when restricted to extraprostatic disease. Conclusion High intake of cruciferous vegetables, including broccoli and cauliflower, may be associated with reduced risk of aggressive prostate cancer, particularly extraprostatic disease.