Atypical femoral fracture in patients with malignant bone metastasis receiving denosumab therapy: Retrospective study.

Abstract

220 Background: While denosumab prevent skeletal-related events in patients with malignant bone metastasis, there are concerns that it may be associated with atypical femoral fracture (AFF). AFF in osteoporotic patients receiving denosumab is reported, but few data have been reported in the context of monthly denosumab therapy for patients with malignant tumor and bone metastasis. Methods: We reviewed the medical records and pharmacy database of patients who received denosumab at 120mg monthly for management of bone metastasis from May 2012 to June 2017 at our institution to analyze the incidence of AFF. To identify the risk factors and optimal management of AFF, we reviewed the clinical features and skeletal images of the patients. Results: We analyzed the data of 204 patients receiving a median of 7 doses (range; 1-60) of denosumab, and 150 (74%) patients received more than three times of denosumab. Four patients were diagnosed as AFF and incidence rate was 2.0%. Five limbs of the 4 patients were diagnosed as AFF and performed intramedullary nail fixation, and 2 limbs of the patients were diagnosed of atypical femoral stress reaction (AFSR) with surgical indication. These patients with AFF received 15, 44, 45 and 45 doses of denosumab, which showed higher doses of denosumab (median: 44.5 doses), compared to the patients without AFF or AFSR (median: 6 doses). Median age of the four patients was 59 (range: 50-66), and primary disease were breast cancer in three patients and non-small lung cell cancer in one patient. Conclusions: We experienced four AFF events among 204 patients receiving denosumab 120mg monthly and incident rate was 2.0%. More data are needed about the occurrence of AFF in these patients.