Prostate cancer screening identifies many men with increased disease risk, e.g. prostate specific antigen (PSA) results below biopsy thresholds and negative prostatic biopsies. There is growing interest in dietary factors like lycopene that may reduce disease risk but little evidence of acceptability in relevant individuals.
The ProDiet trial aimed to establish the feasibility of dietary interventions in men at elevated risk of prostate cancer.
Men aged 50-69 years with PSA values just below biopsy recommendations (2.0-2.95 ng/ml) or negative biopsies identified through the community-based Prostate cancer testing and Treatment trial (ProtecT) were randomized to daily lycopene and green tea or placebo for 6 months in a factorial design. Lycopene and green tea (epigallocatechin) levels were measured in serum taken at baseline and 6 months.
133 men were randomized (34% of 469 invited, remainder declined the invitation): 44 to lycopene capsules, 45 to placebo capsules and 44 to a lycopene-rich diet; 45 to green tea capsules, 43 to placebo capsules, 45 to green tea drink and 127 completed follow-up (95%). At 6 months, mean lycopene values were 25.4 % greater in the dietary advice group (95% CI 1.07-1.46) and 41.9% greater in the lycopene capsule group (95% CI 1.22-1.66) than in the placebo group. Median epigallocatechin levels were 22.1 nM greater in the dietary advice group (95% CI 2.59-41.61) and 9.5 nM greater in the green tea capsule group (95% CI -1.79-20.79) than in the placebo group. Mean PSA levels, blood pressure and weight were unaltered in all groups. Most men would participate in a longer trial (99/133, 74%).
Conclusions: Men adhered successfully to dietary interventions with raised green tea and lycopene levels at 6 months. Evidence-based dietary interventions for men at risk of prostate cancer would seem to be feasible and acceptable.