Alteration of bone quality and prevalence of fragility fractures in patients with breast cancer treated with aromatase inhibitors. A case-control study

Purpose: to study the possible association between long-term treatment with aromatase inhibitors and deteriorated bone quantity and quality in postmenopausal women with breast cancer, leading to a higher prevalence of osteoporosis and fragility fractures. Methods: case and control study. One hundred and four women with breast cancer who had been taking AIs for a median of 3 years were the cases and 104 women of similar age, height and weight made up the control group. We measured biochemical parameters of bone remodeling, vitamin D (25HCC) and PTH. Bone mineral density was determined by bone densitometry in the lumbar spine and in the proximal femur, and TBS in the lumbar spine. Finally, QUS parameters of the dominant foot were estimated. Results: 46.3 % of patients had osteoporosis compared to 16.1 % of controls 38.4 % of these women had suffered at least one fragility fracture, compared to 20.1 % of controls. Women with AI had lower values of bone mass as well as QUS and TBS. Only 9.6 % of women receiving AI had optimal 25HCC levels (greater than 30 ng/mL) compared to 20.2 % of controls. In the logistic regression analysis, the variables associated with the presence of fragility fractures were the time taking AI, vitamin D levels, TBS and beta-crosslaps (CTX). TBS correlated with QUI (r = 0.754. p < 0.01). Conclusions: AIs cause a decrease of bone mass and an alteration in bone quality which increase the risk of fractures. After having had AI for at least 3 years, 46.3 % had densitometric osteoporosis and 38.4 % had suffered at least one fragility fracture. Less than half of the patients had prescribed calcium and vitamin D and less than 20 % some drug for osteoporosis.