TUESDAY, May 21, 2019 (Pharmacist's Briefing) -- The FRAX fracture risk tool can stratify fracture risk equally well among women receiving aromatase inhibitor (AI) therapy for breast cancer and nonusers of AI therapy, according to a study published online May 9 in the Journal of Bone and Mineral Research.
William D. Leslie, M.D., from the University of Manitoba in Winnipeg, Canada, and colleagues used a population-based registry for the province of Manitoba to identify women aged ≥40 years initiating AI for breast cancer with at least 12 months of AI exposure (1,775 participants), women with breast cancer not receiving AI (1,016 participants), and women from the general population (34,205 participants).
The researchers found that among AI users, fracture probability estimated without bone mineral density (BMD; AI use coded as secondary osteoporosis) significantly overestimated risk (10-year observed/predicted ratio, 0.56; 10-year hip fracture observed/predicted ratio, 0.33). With inclusion of BMD in fracture probability, there was no significant difference between observed and predicted fracture risk. FRAX stratified risk for major osteoporotic fracture (MOF), hip, and any fracture equally well in all subgroups (P-interaction > 0.1). AI users were at significantly lower risk for MOF (hazard ratio [HR], 0.78), hip fracture (HR, 0.46), and any fracture (HR, 0.75) when adjusting for FRAX score without BMD. When AI use was not entered as secondary osteoporosis in FRAX without BMD or when BMD was included in the FRAX calculation, AI use was no longer significantly associated with fractures.
"We hope that our data will help to inform clinical guidelines regarding fracture risk assessment in women with breast cancer, and the incorporation of FRAX in management algorithms of those receiving aromatase inhibitors," Leslie said in a statement.
Several authors disclosed financial ties to the pharmaceutical industry.