[Vitamin D deficiency among women diagnosed with breast cancer and unclear benefits of vitamin supplementation].

Breast cancer is the most common cancer in the world and also in Poland. Morbidity for breast cancer is increasing, but mortality rate is still on the same level. In Poland morbidity has increased almost two times during the last 30 years. Vitamin D deficiency in the general population is a common phenomenon, especially among obese and elder. It increases the risk of development and worsens the prognosis in breast cancer. In recent years, the role of vitamin D and its nuclear receptor (VDR) in cancer epidemiology, and its impact on the regulation of immune processes have raised interest. VDR acts as ligand-activated transcription factor. Recent studies suggest a role of vitamin D in the regulation of energy pathways in tumor cells. Another observation on vitamin D is its inhibitory effect on inflammation and regulation of glucose metabolism in neoplastic cell. This article explores the available literature on the effect of vitamin D supplementation in women with breast cancer, describes the potential regulatory vitamin D depend mechanisms occurring in the breast cancer. Due to the limited data on the efficacy and safety, the optimal dose of vitamin D in supplementation of patients with cancer breast has not been determined.