Extending recurrence-free survival superior to TAM. However, AIs put patients at high risk of fractures due to the central role of estrogen in maintaining normal bone metabolism. In contrast, TAM is generally believed to be bone-conserving. Several expert groups have developed guidelines for evaluating fracture risk in breast cancer patients who are planning to start AI therapy, so that the benefits and harms of AIs can be carefully assessed to make an educated decision on choice of hormonal therapy. The aforementioned guidelines vary slightly but usually include bone mineral density testing and clinical assessment of risk factors for fracture. Although BMD remains a strong predictor for fracture risk, several studies have shown that a large proportion of patients who experienced fragility fractures had Tscores in the non-osteoporotic range, which highlights the importance of evaluation of BMD-independent risk factors, such as a priori bone health history, age, physical KRX-0401 activity, smoking, and alcohol intake. However, to our knowledge, only a few small studies have examined bone health history among AI users prior to breast cancer diagnosis, and no studies have investigated lifestyle factors and prior risk of fracture in this patient population. In a real-world clinical setting, it is unknown how bone health history would affect hormonal therapy choice among postmenopausal women with HR-positive breast cancer. These data will be important to inform treatment and prevention strategies for AI users as a high-risk population for bone morbidity. Furthermore, it is of clinical significance to also examine whether known risk factors for fractures are also relevant in breast cancer 
patients, PB 203580 citations considering the paradoxical role of estrogens in promoting carcinogenesis yet maintaining bone health. In a cross-sectional analysis of one of the largest contemporary cohorts of breast cancer patients, we describe history of osteoporosis and fracture and the prevalence of risk factors for fracture, physical activity, smoking, alcohol intake, and calcium and vitamin D supplement use) before breast cancer diagnosis among initial AI users. We also compare prevalence of bone health history in postmenopausal AI users with postmenopausal TAM users. Lastly, we examine associations of these fracture risk factors with prior history of osteoporosis and fracture outcomes in AI users. The baseline interview was conducted at enrollment into the cohort approximately two months post-diagnosis, and included interviewer and self-administered questionnaires on sociodemographics, diet, physical activity, smoking, established breast cancer risk factors, health history, and use of vitamin/mineral supplements. Anthropometric measures were also obtained at baseline. Information was collected on hysterectomy and oophorectomy and associated dates of the surgery, and age or date of last period. Menopause was defined as the absence of menses for 12 consecutive months or more relative to the date of the baseline interview, or having a complete hysterectomy or oophorectomy of both ovaries. In a large contemporary cohort of breast cancer survivors who were initially treated with AIs, we found that 11.2% had a prior history of osteoporosis, 16.3% any fracture, and 4.6% major fracture before breast cancer diagnosis. Although the majority of postmenopausal women were initially treated with AIs, a sizable proportion was initially treated with TAM. Furthermore, these TAM users had nearly twice the prevalence of prior osteoporosis compared with initial AI users. Finally, the associations of selected risk factors with prior history of bone health outcomes in breast cancer patients initially treated with AIs were largely consistent with those expected from the healthy older population.