Another study of 497 breast cancer patients also at the onset of AI therapy found 19.1% with non-vertebral fractures. Compared with our prevalence findings of 11.2% osteoporosis and 16.3% any fracture, Servitja et al. reported a Zelboraf higher rate of osteoporosis but a lower rate of fracture, whereas Bouvard et al. reported a higher rate of fracture. While these studies were limited by small sample size, they did BI-D1870 S6 Kinase? inhibitor collect baseline bone health measures of BMD, spinal X-rays, and 25-hydroxyvitamin D concentrations. Our current analysis does not consider these data, yet in future prospective analyses of fracture risk, we will be incorporating BMD measures and 25D concentrations around baseline entry into the cohort. For postmenopausal women diagnosed with early stage, HRpositive breast cancer, AIs have been shown to have superior efficacy in lowering risk of recurrence compared with TAM, and thus have become the preferable choice for this patient subgroup. However, TAM remains a viable choice for initial hormonal therapy for those who seek to avoid AIs’ musculoskeletal effects. This is likely true for women deemed to have low risk of recurrence but are susceptible to fractures, as suggested by our results. In postmenopausal patients in our study, initial TAM users were slightly younger than initial AI users, yet the former had significantly higher prevalence of osteoporosis history. However, initial TAM users were more likely to have stage I disease than initial AI users, suggesting their risk of recurrence was lower. A lower risk of recurrence coupled with a higher risk of fracture might have influenced physicians and patients to favor TAM over AIs as their first -Pugnac-chemical-structure.gif)
choice of initial hormonal therapy. This speculation was further strengthened by the findings of higher usage of calcium and/or vitamin D supplement and higher physical activity in the initial TAM users than in the initial AI users. As supplement use and physical activity were surveyed soon after breast cancer diagnosis, we could not assess whether these data represent exposure status before or after the diagnosis of osteoporosis. Higher usage of supplements and being more physically active might have been in response to being diagnosed with osteoporosis. It is also interesting to note that a small proportion of initial AI users were diagnosed with breast cancer before menopause. Most likely those patients experienced menopause due to chemotherapy or radiation therapy and were subsequently eligible for AI therapy. Among initial AI users, we identified several risk factors associated with history of osteoporosis, including older age, Asian race, and lower BMI. Older age was also associated with fracture history and being physically active was associated with lower risk of major prior fracture. These associations were in the same direction as expected in a general healthy older population, suggesting common mechanisms for osteoporosis and fracture regardless of later breast cancer diagnosis. Although smoking and alcohol consumption are risk factors for osteoporosis and fracture in non-cancer patients, we did not find such associations in initial AI users, possibly due to the small proportion of current smokers in the study and light alcohol intake in the cohort. We also found that Asian AI users had a higher risk of osteoporosis but lower risk of prior fracture than Whites. This observation potentially reflects known racial/ethnic differences of lower bone mineral density, yet decreased fracture risk, in healthy Asians compared with Whites. When comparing our proportion of prior fracture to healthy postmenopausal women at a similar age in the Women’s Health Initiative, initial postmenopausal AI users were approximately two times less likely to have a history of fracture.