الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
I
n females, breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death, followed by colorectal and lung cancer (for incidence), and vice versa (for mortality).
There are many risk factors for breast cancer like age, density of breast tissue, benign breast conditions, early menarche, late menopause, previous chest exposure to radiation, exposure to diethylstilbestrol and genetic risk factors (BRCA-1 and BRCA-2). As for the risk factors that may differ across patients, they include diet, breast feeding, alcohol consumption, obesity and insufficient physical activity.
Vitamin D is a fat soluble vitamin that plays a role in calcium and phosphorus homeostasis. Recently, extensive research on its extraskeletal actions has linked vitamin D deficiency to an increased risk of infection, diabetes mellitus types 1 and 2, cardiovascular disease, obesity, asthma, inflammatory bowel disease, colon, breast, prostate and ovarian cancer and some neurological diseases. There are various mechanisms by which vitamin D influences the natural history of cancer. These include the role of vitamin D in the induction of apoptosis, stimulation of cell differentiation, anti-inflammatory and antiproliferative effects and inhibition of angiogenesis, invasion and metastasis.
Higher vitamin D exposure is thought to prevent breast cancer through genomic effect modulated by vitamin D receptor (VDR). The finding that vitamin D receptors (VDR) are present in cells throughout the body, and not restricted to bone, intestine and kidney, has led to the rapidly expanding body of research suggesting that vitamin D may be associated with reduced risk of all-cause mortality, some autoimmune diseases (in particular multiple sclerosis), certain cancers, and other chronic diseases.
A great interest in the genetically determined differences in the VDR signaling pathway in relation to disease susceptibility is considered. A number of common allelic variants (or polymorphisms) in the human VDR gene were identified and these were extensively studied with respect to risk for a variety of diseases including breast cancer. The best-studied VDR polymorphisms include a start codon polymorphism (FokI) in exon 2, BsmI and ApaI polymorphisms in an intronic region between exons VIII and IX, a TaqI variant in exon IX and a singlet (A) repeat in exon IX.
Peripheral blood was obtained from seventy-five female patients with breast cancer at different stages and 25 subjects as a control. For every blood sample Breast Tumor Marker CA15.3, Vitamin D, Calcium, PCR for VDR gene FOK1 and RFLP technique for investigating the DNA polymorphism.
The results obtained from each group of breast cancer stage were compared with other groups and with the control group of healthy individuals.
It is concluded that this study provide an additional proof that no association between VDR Fok1 polymorphism genotypes and breast cancer risk and suggest more study for the link between FF genotype and breast cancer.