SAT-729 Prediction of Vertebral Fractures in Breast Cancer Women Undergoing Endocrine Hormone Therapy

Abstract Disclosure: R. Kollar: None. Background and aims: Breast cancer (BC) is the most common malignancy of women worldwide. Although hormone receptor positive (HRP) BC responds well to endocrine hormone therapy (EHT), bone loss and increase risk of fractures are also induced. Vertebral fractures (VF) are underdiagnosed and escape clinical detection because they are asymptomatic at the time of occurrence. Trabecular bone score (TBS) and VFA have been developed, showing good correlation with morphometric bone parameters and in BC women undergoing EHT can lead to early diagnosis of osteoporosis and the identification of high-risk patients for fractures. Material and methods: In total 408 EHT treated, pre- and postmenopausal HRP BC women were enrolled and grouped according to their type of treatment: aromatase inhibitors (AI), AI + gonadotropin-releasing hormone (GAI), gonadotropin-releasing hormone (G), and G + selective estrogen receptor modulators (G + SERM). 236 subjects were excluded based on exclusion criteria, leaving 172 patients for analysis. Spine, hip, and forearm BMD were measured by DXA, and TBS was calculated from L1-L4 spine BMD. VFA was carried out on Th5-L4 vertebral bodies. QUS derived stiffness was assessed at calcaneal site. Results were retrospectively collected, and FRAX was calculated with/without fracture. Results: Our study showed that 13% (n= 23) of EHT treated BC premenopausal women developed morphometric VFs. We compared the prevalence of fractures and VF based on normal, osteopenia, and osteoporosis T-scores. In the normal T-score range, 53 patients were identified, of which 3 had fractures and 7 had VF confirmed by VFA. In the osteopenia group, a total of 83 patients were identified, of which 18 had fractures and 11 had VF. Among the 36 patients diagnosed with osteoporosis, 12 had fractures, and 5 had VF confirmed by VFA. A total of 78% of VF occurred in patients with either normal bone density or osteopenia. At first, we calculated FRAX scores without considering fractures confirmed by VFA (FRAX HIP: 0.8 ± 1.4; FRAX MOP: 7.6 ± 7.3), as these were unknown prior to VFA. However, when a VF confirmed by VFA was included, the FRAX score was significantly higher (FRAX HIP: 4.1 ± 3.5; FRAX MOP: 9.3 ± 7.6). Conclusion: The negative consequences of EHT on bone in premenopausal women have impact of BMD loss and deterioration of bone microarchitecture. Morphometric VFs related to osteoporosis are underdiagnosed and underestimated. It is necessary to identify patients with normal bone density or osteopenia who are at increased risk, such as those with BC receiving EHT. The fracture risk can be further worsened if a fracture is not considered because we did not recognize it. Therefore, it is important to look for VF verified by VFA and take them into account in the FRAX calculation. Fractures determined in this way increase the FRAX value by calculating fracture risk and thus influence our therapeutic approach. Presentation: Saturday, July 12, 2025