Health Professionals Follow-Up Study (HPFS) from 1986 through January 31, 1992, suggest that frequent intake of tomato products or lycopene, a carotenoid from tomatoes, is associated with reduced risk of prostate cancer. Overall, however, the data are inconclusive. We evaluated additional data from the HPFS to determine if the association would persist. Methods: We ascertained prostate cancer cases from 1986 through January 31, 1998, among 47365 HPFS participants who completed dietary questionnaires in 1986, 1990, and 1994. We used pooled logistic regression to compute multivariate relative risks (RR) and 95% confidence intervals (CIs). All statistical tests were twosided. Results: From 1986 through January 31, 1998, 2481 men in the study developed prostate cancer. Results for the period from 1992 through 1998 confirmed our previous findings—that frequent tomato or lycopene intake was associated with a reduced risk of prostate cancer. Similarly, for the entire period of 1986 through 1998, using the cumulative average of the three dietary questionnaires, lycopene intake was associated with reduced risk of prostate cancer (RR for high versus low quintiles= 0.84; 95% CI= 0.73 to 0.96; Ptrend=. 003); intake of tomato sauce, the primary source of bioavailable lycopene, was associated with an even greater reduction in prostate cancer risk (RR for 2+ servings/week versus< 1 serving/month= 0.77; 95% CI= 0.66 to 0.90; Ptrend<. 001), especially for extraprostatic cancers (RR= 0.65; 95% CI= 0.42 to 0.99). These associations persisted in analyses controlling for fruit and vegetable consumption and for olive oil use (a marker for Mediterranean diet) and were observed separately in men of Southern European or other Caucasian ancestry. Conclusion: Frequent consumption of tomato products is associated with a lower risk of prostate cancer. The magnitude of the association was moderate enough that it could be missed in a small study or one with substantial errors in measurement or based on a single dietary assessment.[J Natl Cancer Inst 2002; 94: 391–8]

Among the more than 600 carotenoids in plants, only about 14 are found in human tissues (1). Tomato and tomato products contribute to nine of these 14 carotenoids and are the predominant source of lycopene, neurosporene, gamma-carotene, phytoene, and phytofluene. Because lycopene has potent antioxidant properties (2), studies have evaluated its potential anticancer effects, particularly against prostate cancer (3). The epidemiologic evidence based on dietary intake of lycopene or tomato products or circulating lycopene level has been mixed; six studies support a 30%–40% reduction in prostate cancer risk associated with high intakes (4–9), three studies are consistent with a similar reduction in risk (10–12) but the results were not statistically significant, and seven studies do not support an association (13–19). Thus, the association between tomato products