Therapeutic Options for the Management of Aromatase Inhibitor- Associated Bone Loss

Abstract

Background: Breast cancer is the most commonly occurring cancer in women worldwide. Early breast cancer is a kind of invasive neoplasm that has not proliferated beyond the breast or the axillary lymph nodes. Current therapeutic strategies for breast cancer mainly include local therapies such as surgery or radiotherapy and systemic therapies like chemotherapy, endocrine, and targeted therapy. Nowadays, the adjuvant treatment for hormone receptor-positive early breast cancer in postmenopausal women remains the main effective systemic therapy which can improve disease- free survival and overall survival; it involves several endocrine treatment regimens, including Selective Estrogen Receptor Modulators (SERMs), Aromatase Inhibitors (AIs), or a combination of them. AIs have been shown to be more effective in preventing recurrence in postmenopausal women with early breast cancer when compared with tamoxifen, thus representing the standard of care for adjuvant endocrine therapy. Although AIs are usually well-tolerated, they can have some side effects. Apart from the appearance of arthralgias or myalgias and cardiovascular events, AI therapies, reducing already low endogenous postmenopausal estradiol levels, cause increased bone loss and increase fracture risk in postmenopausal women.

Objectives: The objective of this review is to evaluate the therapeutic options in the management of Aromatase Inhibitor-Associated Bone Loss (AIBL).

Methods: We reviewed the current literature dealing with different therapeutic options in the treatment of AIBL.

Results: Clinical practice guidelines recommend a careful evaluation of skeletal health in all women with breast cancer before AI therapy initiation. Adequate calcium and vitamin D intake have also been suggested. Pharmacological attempts to minimize AI-related bone loss have focused on the use of antiresorptive agents, such as bisphosphonates and denosumab to protect bone integrity and reduce the risk of fractures. Furthermore, clinical trials have shown that by making the bone microenvironment less susceptible to breast cancer metastasis, these drugs are able to increase disease- free survival.

Conclusions: AI, that are the pillar of the systemic treatment for patients with hormone receptorpositive breast cancer, are associated with different side effects, and in particular, osteoporosis and fractures. Both bisphosphonates and denosumab are able to prevent this negative effect.

Keywords: Breast cancer; aromatase inhibitor-associated bone loss; aromatase inhibitors; bisphosphonates; bone mineral density; cancer treatment-induced bone loss; denosumab.