Study to determine whether SNPs in CYP17A1, ESR1, and TNRC9 loci correlate with increased breast cancer risk and serum 25-OH vitamin D levels.

e13086Background: Low serum 25-OH vitamin D (25-OH Vit.D) level is associated with a higher risk of breast cancer. Many single nucleotide polymorphisms (SNP) are associated with breast cancer risk, although the mechanisms underlying this association in most cases remain unclear. We attempted to address this issue by determining whether specific SNPs were correlated with breast cancer-associated biomarkers (BM). Methods: We analyzed estrogen receptor (ER)-positive breast cancer patients treated between Jan 2011 and Dec 2014. We measured serum testosterone and 25-OH Vit.D in pre- and post-menopausal women, and also measured estradiol in the latter group. We genotyped 7 individual SNPs both in premenopausal and postmenopausal women. We then looked for correlations between BMs and SNPs in all three genotypes (homozygotes of major alleles, heterozygotes and homozygotes of minor alleles) using the Kruskal-Wallis test. For each SNP locus associated with a trend or significant effect with regard to BM levels, a t...