Abstract
Vitamin D has received attention for its potential to disrupt cancer processes. However,
its effect in the treatment of prostate cancer is controversial. This study aimed
to assess the effect of vitamin D supplementation on patients with prostate cancer.
In the present study, PubMed, Scopus, ISI Web of Science, and Google Scholar were
searched up to September 2017 for trials that evaluated the effect of vitamin D supplementation
on prostate specific antigen (PSA) response, mortality, and its possible side effects
in participants with prostate cancer. The DerSimonian and Laird inverse-weighted random-effects
model was used to pool the effect estimates. Twenty-two studies (16 before-after and
6 randomized controlled trials) were found and included in the meta-analysis. The
analysis of controlled clinical trials revealed that PSA change from baseline [weighted
mean difference (WMD)=–1.66 ng/ml, 95% CI: –0.69, 0.36, p=0.543)], PSA response proportion
(RP=1.18, 95% CI: 0.97, 1.45, p=0.104) and mortality rate (risk ratio (RR)=1.05, 95%
CI: 0.81–1.36; p=0.713) were not significantly different between vitamin D supplementation
and placebo groups. Single arm trials revealed that vitamin D supplementation had
a modest effect on PSA response proportion: 19% of those enrolled had at least a 50%
reduction in PSA by the end of treatment (95% CI: 7% to 31%; p=0.002). Although before-after
studies showed that vitamin D increases the PSA response proportion, it does not seem
that patients with prostate cancer benefit from high dose vitamin D supplementation
and it should not be recommended for the treatment.
Keywords
vitamin D - prostatic neoplasms - PSA response - mortality - systematic review - meta-analysis
