Lycopene/tomato consumption and the risk of prostate cancer: a systematic review and meta-analysis of prospective studies.

Lycopene/tomato has been discussed as a potential effecter in the prevention and therapy of prostate cancer; however, no systematic review has been reported to illustrate its effect recently. In the present study, a meta-analysis was carried out to determine whether intake of lycopene and tomato/tomato products could reduce the risk of prostate cancer. Eleven cohort studies and six nested case-control studies were identified through searching of international journal databases and reference lists of relevant publications. Two reviewers independently assessed the study quality and extracted data from each identified study; only studies with sufficient quality were included in the review. The main outcome of interest was incidence of prostate cancer. Compared with consumers of lower raw tomato intake, the odds ratio (OR) of incidence of prostate cancer among consumers of higher raw tomato intake was 0.81 [95% confidential interval (CI) 0.59-1.10]; for consumers of higher level of cooked tomato intake versus lower cooked tomato intake, this OR was 0.85 (95% CI 0.69-1.06); the OR of higher lycopene intake versus lower lycopene intake for prostate cancer was 0.93 (95% CI 0.86-1.01) and the OR for higher level of serum lycopene versus lower serum lycopene level was 0.97 (95% CI 0.88-1.08). It's suggested that tomato may play a modest role in the prevention of prostate cancer. Further research would be needed to determine the type and quantity of tomato products regarding their potential in preventing prostate cancer.