Background: Tomatoes and tomato products are the primary dietary sources of lycopene. Frequent intake of tomato products, or lycopene, has been hypothesized to reduce the risk of prostate cancer, but results from previous epidemiologic studies have been mixed. Thus, the relation of tomato products and lycopene to prostate cancer risk remains controversial. Methods: A cohort of 319,365 U.S. men aged 50 to 69 without a cancer diagnosis in 1995 was followed for 5 years. A self-administered 124-item food-frequency questionnaire was used to assess usual dietary intake at baseline. Lycopene intake was calculated using a food composition database derived from national survey data. Incident cases of prostate cancer were ascertained by matching NIH-AARP cohort participants to state cancer registries. Multivariate relative risks (RR) and 95% confidence intervals (CI) of prostate cancer associated with intakes of tomato products and lycopene were estimated from Cox proportional hazards regression models. Results: During 1,420,897 person-years of follow-up, 11,200 total prostate cancer cases were documented. The range of tomato product intake in this population ranged from 1.5 servings/week in the bottom quintile to 8.7 servings/week in the top quintile. There was no association between most quintiles of tomato product intake and prostate cancer, although a statistically significant decrease in risk was noted for men in the top quintile. The RRs of prostate cancer corresponding to increasing quintiles of tomato products were 1.0, 0.98, 0.96, 1.02, and 0.92 (95% CI=0.86-0.97) after adjusting for age and 16 other purported risk factors for prostate cancer. When individual tomato products were examined comparing the top to bottom quintile, weak inverse, but statistically non-significant associations were noted for intake of tomatoes (RR=0.96; 95% CI=0.90-1.02), tomato juice (RR=0.98; 95% CI=0.92-1.04), tomato sauce without meat (RR=0.98; 95% CI=0.92-1.05), pizza (RR=0.97; 95% CI=0.91-1.03), salsa (RR=0.95; 95% CI=0.89-1.01), and chili sauce (RR=0.97; 95% CI=0.91-1.03). In contrast, weak positive, but statistically non-significant associations were noted for intake of tomato/vegetable soup (RR=1.05; 95% CI=0.99-1.11) and tomato sauce with meat (RR=1.06; 95% CI=0.99-1.13). The relation of lycopene to prostate cancer was similar to that seen with overall tomato product intake. The RRs of prostate cancer across increasing quintiles of lycopene were 1.0, 0.99, 1.00, 0.98, and 0.94 (95% CI=0.89-1.01). The RR of prostate cancer comparing the high versus low decile of lycopene was 0.89 (95% CI=0.82-0.97). Analyses of tomato products and lycopene in relation to metastatic and fatal prostate cancer endpoints are currently underway. Conclusion: The results from this large prospective study suggest that frequent intake of tomato products weakly protects against total prostate cancer.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]