Association between genetic variants at 9p21 locus with risk of breast cancer: A systematic review and meta-analysis.

Breast cancer (BC) is the most frequent tumor in women and genetic factors are among the main risk factors contributing to this malignancy. Chromosome 9p21 contains important regulatory non-coding RNAs and is associated with multiple malignancies including BC. The current meta-analysis aimed to investigate the association between genetic variants within the 9p21 locus and risk of breast cancer. A literature search was performed using PubMed, Web of Science, Embase, MEDLINE, Scopus and Clinical key databases. Nine studies containing 23,726 subjects were eligible for the final analysis and specific odds ratios (OR) and confidence intervals (95% CI) were evaluated to assess the strength of the associations. In the pooled analysis, there was an association between the genetic variations in 9p21 locus (CDKN2A/2B) with risk of breast cancer with a standard OR of 1.22 (95% CI: 1.04-1.45, P = 0.016; random-effects model), supporting the significance of this locus as a novel risk factor for breast cancer patients. In conclusion, our results showed that 9p21 region is positively associated with risk of BC and its polymorphisms may be a candidate marker for BC susceptibility.