Vitamin D and prevention of breast cancer
Apart from classical actions of vitamin D on bone and mineral metabolism, it exerts diverse protective biological effects against carcinogenesis. Vitamin D may play role in controlling growth of normal breast cells and may help in prevention of growth of malignant mammary cells. Hypovitaminosis D is gaining attention as an emerging risk factor of breast cancer. Some ecological studies suggest association of high levels of sunlight exposure with low prevalence of breast cancer and mortality rates.
Hence interest arose among researchers with the hypothesis that high levels of vitamin D might help to reduce the risk of breast cancer. Several mechanisms proposed to link deficiency of vitamin D with breast cancer. Numerous epidemiological, laboratory and observational studies demonstrated evidence linking higher vitamin D exposures to reduce prevalence of breast cancer.
Vitamin D deficiency is potentially modifiable risk factor for breast cancer that can be targeted for prevention of the disease. But its safety, feasibility, effect on biomarkers and long term follow up after supplementation is the chief concerns for its use in chemoprevention of breast cancer.
Definite conclusive data from randomized controlled trials about beneficial effect of vitamin D supplementation in prevention of breast cancer is lacking. Serum 25(OH) D is the chief form of circulating vitamin D and most accepted marker of vitamin D status. It is widely used clinical laboratory test to evaluate vitamin D deficiency. In the present review, we attempted to address the issue of vitamin D status as a risk factor for breast cancer and its potential use as chemopreventive therapeutic agent.