gms | German Medical Science

Introduction: Prostate cancer is the most common cancer in men with increasing incidence in Western countries. Lycopene intake by tomato consumption was suggested to decrease risk. However, this has not been studied thoroughly in a prospective study in Germany nor was effect modification by specific characteristics of the tumour considered.

Material & Methods: Within the Heidelberg European Prospective Investigation into Cancer and Nutrition (EPIC) cohort with a median follow-up time of 8.0 years 171 prostate cancer cases were identified. Histological characteristics of tumours and PSA values before biopsy were collected by reviewing medical records. At recruitment, all study participants completed a validated dietary questionnaire. Risk evaluations were performed by means of Cox proportional hazard models, comparing cases with 10735 disease free controls. We adjusted for age, BMI, education, smoking status, total energy intake.

Results: Intake of raw tomatoes, cooked tomatoes and tomato sauces was not significantly related to disease risk. A high intake of tomato puree was inversely associated with prostate cancer risk. The crude odds ratios (OR) were 0.87 (95% CI 0.62-1.23) in the 2nd and 0.50 (95% CI 0.34-0.75) in the 3rd tertile as compared to the lowest intake tertile. After adjustment the results were slightly attenuated with 0.97 (95% CI 0.69-1.36) in the 2nd and 0.58 (95% CI 0.39-0.87) in the third tertile (p trend = 0.01). This inverse association was more pronounced for the intake of tomato puree and locally confined prostate cancer with an OR of 0.53 (95% CI 0.33-0.84) in the 3rd tertile (p trend = 0.01) as well as non-T1-tumors with an OR of 0.50 (95% CI 0.32-0.79) for the highest tertile (p trend = 0.004). Overall, the strongest risk reduction was found for poorly differentiated, highly malignant tumours (WHO grade III) with an OR of 0.32 (95% CI 0.12-0.89; p trend = 0.03) in the 3rd tertile as compared to the lowest intake category.

Discussion: The results support previous findings from US cohort studies. The carotenoid lycopene is proposed to be causally related and it is known that its bioavailability is higher in processed tomato products such as puree.

Conclusion: In this study, a diet rich in tomato puree is associated with a decrease in prostate cancer risk by almost 50 %. This favourable effect seems even more pronounced in large or highly malignant tumours.