BACKGROUNDBreast cancer is the most common type of cancer among females. Genetic polymorphisms might have a role in carcinogenesis. The aim of this study was to determine whether C to T base substitution within TaqI Vitamin D receptor (VDR) gene (rs731236) in exon 9 was a risk factor among patients with breast cancer.

METHODSPeripheral blood was drawn from 122 Jordanian breast cancer patients and 100 healthy Jordanian volunteers in Al-Basheer Hospital during the summer months (from June to November of 2013, 2014, and 2015). DNA was amplified using polymerase chain reaction (PCR), followed by TaqI restriction enzyme digestion. Quantification of serum 25-hydroxy Vitamin D (25[OH]D) level was determined by competitive immunoassay Elecsys.

RESULTSGenotypic frequencies for TaqI TT, Tt, and tt genotypes were 41%, 46%, and 13% for breast cancer compared to 42%, 50%, and 8% for control, respectively. Vitamin D serum level was significantly lower in the breast cancer patients (8.1 ± 0.3 ng/ml) compared to the control group (21.2 ± 0.6 ng/ml; P= 0.001). This study showed an inverse association between 25(OH)D serum level and breast cancer risk (odds ratio [OR], 22.72, 95% confidence interval [CI], 10.06-51.29).

CONCLUSIONSAn inverse association was found between 25(OH)D serum level and breast cancer risk. Statistical difference was also found between different VDR TaqI genotypes and circulating levels of 25(OH)D among Jordanian females with breast cancer.