PTGS2 and breast cancer: The present meta-analysis, including 15,330 cases and 19,260 controls from 13 case-control studies, was conducted to evaluate the association between the three common SNPs [−765 G>C (rs20417), −1195 G>A (rs689466), and 8473 C>T (rs5275)] in the COX-2 gene and breast cancer risk.