Vitamin D and Sun Exposure with Premenopausal Breast Cancer in Rural Iran

Vitamin D is one of the critical factors for female reproductive health which may have protective activities against many cancer types, including breast cancer. This vitamin is a secosteroid hormone which regulates the expression of a large number of genes in reproductive tissues which could emphasize the important role of this vitamin in female reproduction and health (Shao, et al., 2013). Vitamin D could be obtained mainly through sunlight exposure and in the absence of sufficient sunlight exposure; vitamin D deficiency may occur rapidly (Looker et al., 2008). Although individual factors like skin pigmentation and seasons may affect cutaneous synthesis of vitamin D , its deficiency could be correlated by obesity, low levels of dietary intake, lack of sun exposure, and older age (Wortsman et al., 2000). Breast cancer (BC) is the most frequent female cancer (23% of all cancers) and the most fatal form of malignancy among women worldwide. It accounts for more than 16%