The search criteria used the following key words: “Adjuvant endocrine therapy for breast cancer” OR “GnRH agonists” OR “Tamoxifen” OR “Aromatase inhibitor” OR “anastrozole” OR “exemestane” OR “letrozole” AND “bone health” OR “fracture” OR “bone mineral density” OR “bisphosphonates” OR “denosumab”. This evidence concerns the gene GNRH1 and breast cancer.