FDG PET/CT Assesses the Risk of Femoral Pathological Fractures in Patients with Metastatic Breast Cancer

Purpose Assessment of pathological fracture risk is critical to optimize the use of prophylactic orthopedic fixation to prevent pathological fractures. Better prediction of pathological fracture risk is needed. We evaluated if quantitative measures of FDG avidity can assess femoral pathological fracture risk in patients with metastatic breast cancer (MBC). Patients and Methods A Health Insurance Portability and Accountability Act-compliant retrospective case-control study was performed under institutional review board waiver. Patients with MBC who received an FDG PET/CT from January 2008 to December 2014 and had pathological fracture of the proximal femur within 3 months of PET/CT were selected as cases. Patients with MBC who had an FDG PET/CT in 2013 were sequentially screened in reverse chronological order to identify patients with proximal femoral metastases on PET/CT but no subsequent pathological fracture to serve as a control group. The prespecified goal was to have twice the number of controls as cases. Target lesions in the proximal femur, from femoral head to 5 cm below the lesser trochanter, were analyzed on FDG PET/CT for SUV^max, SUV^mean, metabolic tumor volume, and total lesion glycolysis. Wilcoxon rank sum test was used to compare continuous variables in cases and controls. A nonparametric receiver operating characteristic analysis was performed to assess the ability of quantitative FDG measurements to differentiate between cases and controls. Results In 27 cases with pathological fracture and 55 controls without pathological fracture, all 4 quantitative measures of FDG avidity were statistically different between cases and controls (P < 0.001). A total lesion glycolysis of 81 could differentiate between fracture and nonfracture patients with accuracy, sensitivity, and specificity of 0.83, 0.85, and 0.80, respectively. Conclusions Quantitative measures of FDG avidity may help identify breast cancer patients at high risk of subsequent pathological fracture of the proximal femur.