Assessment of Aromatase Inhibitor-Induced Bone Loss and Appropriateness of Supportive Therapy in Postmenopausal Breast Cancer Patients at a Tertiary Care Center

Abstract

Objective: To assess aromatase inhibitor-induced bone loss (AIBL) and its management in postmenopausal women (PMW) with breast cancer (BC). Materials and Methods: A cohort of 350 PMW with BC receiving aromatase inhibitors (AIs) during a span of 4 years was evaluated retrospectively. Bone mineral density (BMD) of the patients at lumbar spine (LS) and dual femur was monitored at baseline and annually for 2 years. Baseline fracture risk was evaluated using WHO fracture risk assessment tool. Results: At baseline, only 35.4% of the patients received supportive therapy such as calcium and Vitamin D supplements ± bisphosphonates. Significant decrease of mean BMD occurred at LS, left femur, and right femur (LF and RF) at 1 year (P < 0.001) in 64.6% of patients who did not receive supportive therapy at baseline. Those who received supportive therapy at baseline had a significant elevation of their mean BMD at LS, LF, and RF; (P < 0.001) at 1 year, and this increase in BMD persisted at 2 years. Ten-year fracture risk at baseline was 'high' for 3.14% of patients, while 35.43% had 'moderate risk' of major osteoporotic fracture and 26.6% had 'high risk' of hip fracture. Overall incidence of fractures was 1.1% in patients who did not receive supportive therapy from baseline to 1 year. Conclusion: Majority of BC patients on AIs were not prescribed supportive therapy at baseline. Since AI monotherapy caused significant loss of LS and dual femur BMD at 1 year of treatment, up-front supportive therapy should be started concurrently with AIs from baseline for the prevention of AIBL.