ProDiet: A Phase II Randomized Placebo-Controlled Trial of Green Tea Catechins and Lycopene in Men at Increased Risk of Prostate Cancer

Epidemiological studies suggest that diet can alter prostate cancer risk. This study aimed to establish the feasibility and acceptability of dietary modification in men at increased risk of prostate cancer. Men were invited with a prostate specific antigen (PSA) level of 2.0-2.95 ng/mL or 3.0-19.95 ng/mL with negative prostate biopsies. Randomization (3x3 factorial design) to daily green tea and lycopene: green tea drink (3 cups, unblinded) or capsules (blinded, 600 mg flavan-3-ol ()-epigallocatechin-3-gallate (EGCG) or placebo) and lycopene-rich foods (unblinded) or capsules (blinded, 15 mg lycopene or placebo) for six months. Primary endpoints were randomization rates and intervention adherence (blinded assessment of metabolites) at six months with secondary endpoints of acceptability (from interviews), safety, weight, blood pressure and PSA. A total of 133/469 (28.4%) men approached agreed to be randomized and 132 were followed-up (99.2%). Mean lycopene was 1.28 (95% confidence intervals (CI) 1.09, 1.50, p = 0.003) times higher in the lycopene capsule group and 1.42 (95% CI 1.21-1.66, p<0.001) times higher in the lycopene-enriched diet group compared to placebo capsules. Median EGCG was 10.7 nM (95% CI 7.0, 32.0) higher in in the active capsule group and 20.0 nM (95% CI 0.0, 19.0) higher in the green tea drink group compared with placebo capsules (both p<0.001). All interventions were acceptable and well tolerated although men preferred the capsules. Dietary prevention is acceptable to men at risk of prostate cancer. This intervention trial demonstrates that a chemoprevention clinical trial is feasible.