AB0998 Osteoporosis prevalence in post-menopausal patients treated with aromatase inhibitors using bone mineral density values from a spanish population

Background The majority of cases of breast cancer (BC) are hormone receptor positive and are sensitive to antiestrogen therapy. For postmenopausal women, adjuvant hormonal therapy with an aromatase inhibitor (AI) is the standard of care, and is associated with greater prevalence of osteoporosis (OP)1. Definition of osteoporosis is made depending on the T-Score value, which is calculated according to the bone mass peak obtained from a reference population; in our country, BMD reference values in clinical practice are obtained from the National Health and Nutrition Examination Survey cohort (NHANES III) for femoral neck (FN) and those proportionated by the commercial brand Hologic for lumbar spine (LS), which may not be representative of our population and could be distorting the assessment of OP in our patients. Objectives To assess the prevalence of OP in Spanish postmenopausal patients diagnosed with BC and treated with AI using BMD values obtained from a local cohort for T-Score calculation. Methods We performed a cross-sectional study with postmenopausal women diagnosed with BC and treated with AI attended in our hospital between August 2011 and December 2014. We estimated BMD for LS and FN using dual X-Ray absorptiometry. The prevalence of OP in our cohort was assessed using BMD reference values from the Spanish cohort of Diaz-Curiel2, which included a group of 2442 healthy patients from both genres stratified by age, and compared it with OP prevalence obtained using clinical practice reference values applied in our country (NHANES III/Hologic). Results A total of 54 patients were included. The mean age at diagnosis was 61.50±6.50 years. The AI used in both groups was letrozole. For LS we didn’t find statistically significant differences between both groups. For FN we found 13 patients (24%) with OP according to NHANES/Hologic, and 8 patients (14.8%) according to Diaz-Curiel values. These values are summarised in the table. Conclusions In our study, we observe statistically significant differences in osteoporosis prevalence for FN, and around 10% of patients could be reclassified using our local BMD values, which highlights the relevance of the use of BMD values obtained from local population for T-score calculation. References [1] Becker T, Lipscombe L, Narod S, Simmons C, Anderson GM, Rochon PA. Systematic review of bone health in older women treated with aromatase inhibitors for early-stage breast cancer. J Am Geriatr Soc2012;60:1761–1767. [2] Diaz Curiel M, Garcia JJ, Carrasco JL, Honorato J, Perez Cano R, Rapado A, et al. Prevalence of osteoporosis assessed by densitometry in the Spanish female population. Med Clin (Barc)2001;116:86–88. Disclosure of Interest None declared