Few studies also confirmed an inverse relationship of OPG serum levels with breast cancer risk in cohorts of primarily premenopausal patients with a BRCA1/2 mutation (mean age 42 years) [35, 36] as well as in the general population for primarily postmenopausal women (mean age 61 years) [37], while another investigation did not find an association in general premenopausal women (median age 44 years) [38]. Here, BRCA1 is linked to breast cancer.