Title:Vitamin D Supplementation and Cancer: Review of Randomized Controlled Trials
VOLUME: 13 ISSUE: 1
Author(s):Matteo Lazzeroni, Davide Serrano, Stefan Pilz and Sara Gandini
Affiliation:Division of Epidemiology and Biostatistics, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy.
Keywords:Vitamin D, Randomized Controlled Trials, Cancer Mortality, Cancer Incidence, vitamin D serum level, ergocalciferol, Cochrane meta-analysis, Osteoporotic Fractures, coronary heart disease, serum 25(OH)D
Abstract:Data from experimental studies suggest that vitamin D receptor activation exerts anti-cancer effects on virtually all steps of
carcinogenesis. Epidemiological data support an inverse association of vitamin D serum levels and vitamin D receptor polymorphisms
with cancer incidence and mortality. Based on this promising rationale for use of vitamin D and its analogues in cancer prevention and
treatment, several interventional studies have been initiated and partially published. Trials with vitamin D were mainly organized for the
prevention of fracture in elderly people, usually in association with calcium supplements. Prevention studies with vitamin D have rarely
been done in the context of vitamin D to evaluate a protective effect on cancer. Findings from prospective cohort studies on colorectal
cancer risk and on mortality constitute pieces of evidence strong enough to consider that previous randomized controlled trials (RCTs) of
vitamin D use and cancer may not have correctly addressed the question, and that new randomized trials should be organized. The
reasons are due to several unsolved issues including selection of the effective dose, varying baseline levels of subjects before
randomization, compliance with the intervention, contamination of the placebo group (i.e., intake of vitamin D supplements by subjects
allocated to the placebo group) and unknown effective lag time between start of the intervention and disease onset. The present review
summarizes the existing knowledge on vitamin D RCTs and cancer. In addition we also briefly describe the design of some ongoing trials
on vitamin D supplementation and cancer.
