Adherence to osteoporosis screening guidelines in seniors with breast cancer treated with anti-estrogen therapy: A population-based study.

Abstract

72 Background: Aromatase inhibitors (AI) improve recurrence and survival rates in women ≥ 65 with hormone-receptor positive (HR+) breast cancer (BC). However, AI’s are associated to increased bone demineralization in a population already at risk for osteoporosis. Bone mineral densitometry (BMD) is therefore recommended at treatment start, to minimize treatment-related toxicity. This study assesses compliance to BMD recommendations in older BC survivors treated with an AI and identifies predictors of non-adherence to guidelines. Methods: A population-based historical prospective cohort study was conducted in Quebec (Canada), where universal health insurance provides medical and pharmaceutical services. All women ≥ 65 with incident stage I, II or III BC (1998-2012) were identified from the provincial cancer registry. Administrative claims were accessed to track receipt of BMD (±12 months from treatment start) and potential predictors: age, economic status, Charlson comorbidity index, breast and axillary surgery, chemotherapy, radiotherapy, bisphosphonate use, adherence to anti-estrogen therapy (AET), physician specialty and having a primary care physician (PCP). Multivariate logistic regression was performed using generalized estimating equations to identify predictors of BMD, adjusting for clustering within physicians. Results: Of 16,480 patients, 36.1% had a BMD at AET start. This increased to 58.4% for women on AI. Factors predicting baseline BMD non-use in AI patients were: older age (OR 0.42; 95% CI, 0.36 – 0.49), lower annual income (OR 0.57; 95%CI, 0.47 – 0.70), not having a PCP (OR 0.77; 95%CI, 0.68 – 0.86), chemotherapy and radiotherapy outside of guidelines (OR 0.80; 95%CI, 0.66 – 0.96 and 0.69; 95%CI, 0.54 – 0.87, respectively), non-surgical specialist managing AET (OR 0.81; 95%CI, 0.67 – 0.98), older physicians (OR 0.61; 95% CI, 0.46 – 0.81), and non-adherence to AET (OR 0.69; 95%CI 0.60-0.79). The same predictors persisted in patients on any AET. Conclusions: Bone health management in seniors receiving AET is suboptimal. Factors related to underutilization of BMD can be easily identified and used to optimize chronic care of older BC survivors.