PTGS2 and breast cancer: Furthermore, HB‐EGF, COX‐2, and Wnt4 as well as Bmp2 have been shown to be risk factors for sex hormone‐dependent diseases, such as prostatic hyperplasia, breast cancer, and ovarian cancer (Bentley et al, 1992; Ferrandina et al, 2002; Levin, 2003; Zong et al, 2012).