Background:There is growing interest in the role of nutritional/dietary and physical activity interventions in the tertiary prevention of prostate cancer progression and mortality, but findings have been conflicting.
Aim:To update previous systematic reviews of randomised controlled trials (RCTs) of nutritional/dietary interventions in men with prostate cancer, and extend the interventions considered to include physical activity.
Methods:AMED, Cinahl, the Cochrane library, Embase, MEDLINE and Web of Science bibliographic databases were searched from inception to January 2014. Our search included RCTs of men with prostate cancer undergoing nutritional/dietary and/or physical activity interventions, which reported on measures of prostate cancer progression or mortality. There were no language restrictions. Papers were screened for eligibility by two independent reviewers. Data from included papers were extracted, analysed and synthesised.
Results:A total of 11,659 papers were retrieved, of which 51 (0.4%) met the inclusion criteria. The median sample size was 54(range 19–383) and the target populations varied, including men awaiting radical prostatectomy (n=13,26%) and active surveillance (n=10,20%). All papers had high (n=40,79%) or medium (n=11,21%) risk of bias. Dietary/nutritional interventions were reported in 30 papers, most commonly being lycopene (n= 7) supplementation. One paper reported a physical activity intervention of resistance and aerobic training. There were 16 complex nutritional/dietary interventions and 4 combined nutritional/dietary and physical activity interventions, including vegan diet and aerobic activity (n=2). Median adherence to the interventions was 90%(range 58-100%).The main adverse events were diarrhoea and nausea. Reported outcomes were heterogeneous and involved: changes in prostate specific antigen (n=43); changes in insulin-like growth factor (n=11) and cell proliferation (n=8). Due to the heterogeneity, formal meta-analysis was not possible.
Conclusions:Studies to date have mostly been small and low quality. Future RCTs need to be adequately powered, well designed (low risk of bias), with carefully chosen interventions and clinically meaningful outcomes.