Association of five single nucleotide polymorphisms at 6q25.1 with breast cancer risk in northwestern China.

CCDC170 and ESR1, located at 6q25.1, were associated with breast cancer (BC) risk by genome-wide association studies. Our goal was to validate the association between CCDC170-ESR1 polymorphisms and BC risk in the population of northwestern China. A case-control study of 551 patients with BC and 577 control individuals was conducted from January 2011 to November 2014. We analyzed five BC-associated single nucleotide polymorphisms (SNPs) identified in CCDC170-ESR1 by previous studies. Logistic regression models were used to derive odds ratios (ORs) and 95% confidence intervals after adjusting for body mass index and age. The minor alleles of rs3757318, rs3734805, and rs2046210 were associated with increased BC risk (OR = 1.30, p = 0.005; OR = 1.28, p = 0.006; OR = 1.20, p = 0.033, respectively) in an allelic model analysis. Those three SNPs had a coincident significant association with increased BC risk in genetic models and stratification analyses. A new haplotype, "CT", was associated with a 1.31-fold increased risk of BC (OR = 1.31, p = 0.006). The "C" allele of rs9383951 was associated with a reduced risk of BC (OR = 0.69, p = 0.048) in estrogen receptor-positive individuals under the log-additive model. Our data provide new evidence of the association between CCDC170-ESR1 and BC susceptibility in the population of northwestern China.