Recommendations for antiresorptive therapy in postmenopausal patients with breast cancer: Marburg AIBL Guideline Evaluation Study (MAGES)

Postmenopausal women with hormone-receptor-positive breast cancer usually receive aromatase inhibitor (AI) therapy at some point in their disease management. Accelerated bone loss during AI therapy poses a problem, especially in postmenopausal women who may already have age-related osteopenia or several fracture-related risk factors. Guidelines and algorithms have been developed to identify women at risk for fractures from low bone mineral density and to provide recommendations for antiresorptive treatment. However, the factors used to calculate fracture risk and the thresholds for antiresorptive treatment vary among the current guidelines and algorithms, potentially leading to inconsistent recommendations for or against antiresorptive treatment. The present study analyzed antiresorptive treatment decisions in a population of postmenopausal women with hormone-receptor-positive breast cancer receiving AI therapy using five different guidelines/algorithms (World Health Organization Fracture Risk Assessment tool [FRAX], expert consensus, German Dachverband Osteologie, American Society of Clinical Oncology, and World Health Organization). The consistency of a recommendation for antiresorptive treatment among the five methods was low (4 %). The consistency of a recommendation against antiresorptive treatment among the five methods was higher (57 %), but left approximately 40 % of patients with an inconsistent recommendation. The consequences of overtreatment (unnecessary exposure to adverse events) and undertreatment (increased risk of fractures and possibly decreased disease-free survival) make it imperative that the existing guidelines and algorithms be improved. Moreover, evidence-based outcomes from antiresorptive treatment decisions are required to validate guidelines and algorithms.