A feasibility randomised controlled trial of dietary interventions for prostate cancer prevention: ProDiet


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J Athene Lane1, David Gillatt2, Jeff Holly1, Richard Martin1, Alan Crozier3, Marie Cantwell4, Freddie Hamdy5, David Neal6, Jenny Donovan1, Chris Metcalfe1
1University of Bristol, Bristol, UK, 2North Bristol Trust, Bristol, UK, 3University of Glasgow, Glasgow, UK, 4Queen's University of Belfast, Belfast, UK, 5University of Oxford, Oxford, UK, 6Addenbokes's Hospital, Cambridge, UK

Background

Prostate specific antigen (PSA) testing identifies some men with elevated PSA levels below biopsy thresholds and others without cancer at biopsy who also have an increased risk of prostate cancer. The ProDiet trial aimed to establish the feasibility of dietary intervention as diet and lifestyle modification could potentially lower cancer risk.

Method

Men aged 50-69 years identified through community-based PSA testing in the Prostate cancer testing and Treatment trial1 with PSA results between 2.0 -2.95 ng/ml or negative biopsies were randomised to daily lycopene (44 to active capsules, 44 placebo and 45 lycopene-rich diet) and green tea (45 active capsules, 45 placebo, 43 tea drink) for 6 months. The primary outcome of lycopene and green tea (epigallocatechin) serum values at baseline and 6 months were measured in laboratories blinded to allocation.

Results

133/469 men invited were randomised (34%) and 124 completed follow-up (93%). Initial results show that the mean serum lycopene values increased in the dietary (difference = 0.15 ┬Ámol/L, 17% increase from baseline, p = 0.004) and active groups (0.31 ┬Ámol/L, 32% p <0.0001) and were unchanged in the placebo group (0.05, 7% p = 0.25). Mean serum values also increased in the green tea drink (difference = 35.4 nM, 94% p< 0.0001) and active groups (23.3 nM, 95% p <0.0009) and were unchanged in the placebo group (0.09 nM, -5% p = 0.95). There were no significant changes in PSA, blood pressure or weight in any randomised group at 6 months. Most men would consider participating in a longer trial (99/133, 74%).

Conclusion

Men adhered successfully to two dietary interventions with significant elevation of serum green tea and lycopene levels at 6 months. A dietary prevention trial for men at an elevated risk of prostate cancer would seem be feasible and acceptable.