Tomato consumption and prostate cancer risk: a systematic review and meta-analysis.

Previous studies have reported controversial results on the association between tomato consumption and prostate cancer risk. Hence, we performed a meta-analysis to comprehensively evaluate this relationship. A total of 24 published studies with 15,099 cases were included. Relative risks (RR) and 95% confidence intervals (CI) were pooled with a random-effects model. Tomato intake was associated with a reduced risk of prostate cancer (RR 0.86, 95% CI 0.75-0.98, P = 0.019; P < 0.001 for heterogeneity, I = 72.7%). When stratified by study design, the RRs for case-control and cohort studies were 0.76 (95% CI 0.61-0.94, P = 0.010) and 0.96 (95% CI 0.84-1.10, P = 0.579), respectively. In the subgroup analysis by geographical region, significant protective effects were observed in Asian (RR 0.43, 95% CI 0.22-0.85, P = 0.015) and Oceania populations (RR 0.81, 95% CI 0.67-0.99, P = 0.035), but not in other geographical populations. Begg's test indicated a significant publication bias (P = 0.015). Overall, tomato intake may have a weak protective effect against prostate cancer. Because of the huge heterogeneity and null results in cohort studies, further prospective studies are needed to explore the potential relationship between tomato consumption and prostate cancer risk.