Bone-active drugs in premenopausal women with breast cancer under hormone-deprivation therapies.

Background: Bone health management in premenopausal women with breast cancer (BC) under hormone-deprivation therapies (HDTs) is often challenging, and the effectiveness of bone-active drugs is still unknown.

Methods: This retrospective multicenter study included 306 premenopausal women with early BC undergoing HDTs. Bone mineral density (BMD) and morphometric vertebral fractures (VFs) were assessed 12 months after HDT initiation and then after at least 24 months.

Results: After initial assessment, bone-active drugs were prescribed in 77.5% of women (151 denosumab 60 mg/6 months, 86 bisphosphonates). After 47.0 ± 20.1 months, new VFs were found in 16 women (5.2%). Vertebral fracture risk was significantly associated with obesity (odds ratio [OR] 3.87, P = .028), family history of hip fractures or VFs (OR 3.21, P = .040], chemotherapy-induced menopause (OR 6.48, P < .001), preexisting VFs (OR 25.36, P < .001), baseline T-score less than or equal to -2.5 standard deviation (SD) at any skeletal site (OR 4.14, P = .036), and changes at lumbar and total hip BMD (OR 0.94, P = .038 and OR 0.88, P < .001, respectively). New VFs occurred more frequently in women untreated compared to those treated with bone-active drugs (14/69, 20.8% vs 2/237, 0.8%; P < .001) and the anti-fracture effectiveness remained significant after correction for BMI (OR 0.03; P < .001), family history of fractures (OR 0.03; P < .001), chemotherapy-induced menopause (OR 0.04; P < .001), and preexisting VFs (OR 0.01; P < .001).

Conclusions: Premenopausal women under HDTs are at high risk of VFs in relationship with high BMI, densitometric diagnosis of osteoporosis, preexisting VFs, and family history of osteoporotic fractures. Vertebral fractures in this setting might be effectively prevented by bisphosphonates or denosumab.