Lightning Talk + Poster ESA-SRB-NZSE-CaSR 2026 in conjunction with ENSA

Management of aromatase inhibitor-associated bone loss in women with hormone receptor-positive breast cancer: a single centre experience (143847)

Kimchi Do 1 2 , Anuradha Vasista 3 , Phuong Dinh 3 , Jeremy Mo 3 , Albert S Kim 1 2 , Christian M Girgis 1 2
  1. Department of Diabetes and Endocrinology, Westmead Hospital, Westmead, NSW, Australia
  2. Sydney Medical School, University of Sydney, Camperdown, NSW, Australia
  3. Breast Cancer Institute, Westmead Hospital, Westmead, NSW, Australia

Aromatase inhibitors (AI) are frequently used to treat hormone receptor-positive breast cancers but can accelerate bone loss and increase fracture risk. We aimed to assess management of AI-associated bone loss in a tertiary Osteoporosis Refracture Prevention (ORP) service.

We performed a retrospective audit of pre- and post-menopausal women receiving AI who attended Westmead Hospital’s ORP clinic between February 2019–February 2026. Clinical characteristics, biochemistry, and bone mineral density (BMD) were analysed.

Eighty-seven women were included. Mean age 65±10.8 years. Menopausal age 48±5.7 years (72(83%) natural, 4(5%) surgical, 11(13%) due to goserelin). Letrozole was the most common AI (81/87,93%). Median AI exposure was 3.5(1.8–5.2) years. Median follow-up was 1.5(0.7–2.4) years. Before AI therapy, 82(94%) underwent baseline DEXA; 49(60%) had osteopenia, 29(35%) osteoporosis, and 18(21%) had prior fragility fracture.

Anti-resorptives were prescribed in 77(88%), most commonly zoledronic acid (35/77, 45%; 31 received 5mg annually, 4 received 4mg q6monthly), oral bisphosphonates (25/77, 32%), and denosumab (16/77, 21%). Median time from AI commencement to anti-resorptive therapy was 10(-3–23) months. Bone turnover markers declined over time. Earlier anti-resorptive initiation (<10 months from AI commencement) was associated with greater lumbar spine BMD %change than later initiation (2.48±7.26% vs  -2.46±9.15%;p=0.028). A similar trend was observed at the total hip but was not significant (0.87±6.51% vs  -2.63±5.90%;p=0.053)(Figure 1,2). 

Twelve(14%) sustained a new fragility fracture (including 3 hip fractures) despite anti-resorptives with no new clinical vertebral fractures, 7 of whom had delayed anti-resorptive start. Median time from AI start to fracture was 29(18–60) months. AI therapy was discontinued in 11(13%) due to worsening BMD or incident fracture despite anti-resorptives. 

Anti-resorptives were frequently prescribed and associated with improved lumbar spine BMD, particularly with earlier initiation, supporting timely intervention to mitigate AI-associated bone loss. Development of strategies leading to concurrent initiation of anti-resorptives in at-risk women commencing AIs is warranted.

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