BRCA2 and breast cancer: Recently reported known risk factors, such as mammographic density [2], [3], [4], [5], genetic modifications of interleukin-18 (IL-18) [6], tumor protein 53 (p53), breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2) genes [7], [8], [9] account for approximately 30% of breast cancer cases.