Use of Aromatase Inhibitors in the Treatment of EstrogenDependent Breast Cancer and its Impact on Bone Health

Abstract

With more than 1 in 10 new cancer diagnoses each year, breast cancer is the most common cancer in women and is responsible for being the second leading cause of cancer-related death among women worldwide. Among breast cancers, the majority diagnosed are estrogen-receptor-positive or estrogen-dependent breast cancers. Aromatase inhibitors are an effective form of targeted therapy for patients with estrogen-dependent breast cancer. The selective estrogen-receptor modulator tamoxifen is much less effective than the aromatase inhibitors anastrozole, letrozole, and exemestane in preventing recurrence in early breast cancer that is estrogen receptor positive. Selective estrogen-receptor modulators are expected to be replaced by aromatase inhibitors as the first-line adjunctive treatment for several patients. Third-generation aromatase inhibitors are quickly replacing tamoxifen as the endocrine medication of choice for post-menopausal women with breast cancer due to their superior efficacy in both adjuvant and metastatic settings. Aromatase inhibitor therapy for breast cancer patients undoubtedly provides benefits, particularly in terms of increased disease-free survival, but it may also have detrimental longterm effects on bone health. Lack of estrogen will invariably cause bone loss since any treatment that reduces estrogen could result in bone loss. The use of aromatase inhibitors is associated with an increased risk of fractures and accelerated rates of bone loss. The purpose of this research is to review the available information about the use of aromatase inhibitors in the treatment of estrogen-dependent breast cancer and their impact on bone health.