VDR and breast carcinoma: In addition, polymorphisms in the VDR gene have been associated with increased risk for breast cancer (169, 170) and a meta-analysis of 11 studies on circulating vitamin D levels and breast cancer risk demonstrated a 45% reduction in breast cancer risk among women with the highest levels of 25-hydroxyvitamin D (25(OH)D), the major circulating form of vitamin D (171).