Noninvasive Prediction of Fracture Risk in Patients with Metastatic Cancer to the Spine

Purpose: Skeletal metastases affect up to 85% of breast cancer patients by the time of their death. This prospective in vivo study evaluated the diagnostic performance of computed tomography-based structural rigidity analysis (CTRA) to predict vertebral fracture risk in breast cancer patients with skeletal metastasis and in comparison with the current standard of care. Experimental Design: Torso CT scans of 94 women with vertebral metastatic breast cancer were obtained as part of routine screening for lung and liver metastases. The load-bearing capacity (LBC) and axial (EA) and bending (EI) rigidities of vertebrae T8 to L5 were calculated from CT images. The LBC was normalized by patient body mass index (BMI) to account for height and mass variations. Vertebral fracture risk was also calculated using the current radiographic-based criteria based on lesion size and location. The actual occurrence of a new vertebral fracture was assessed radiographically over the ensuing 4 months. Results: Eleven vertebral fractures occurred in 10 patients. The structural parameters EA, El, LBC, and LBC/BMI were all 100% sensitive and 55%, 53%, 44%, and 70% specific to predict fracture risk, respectively. Although radiographic criteria correctly predicted all fracture cases (100% sensitive), only 48 of the 236 spinal segments that did not have a fracture were correctly predicted not to fracture (20% specific). Conclusions: CTRA, using CT scans as part of routine screening for lung and liver metastasis, is shown to be as sensitive as, and significantly more specific than, the current radiographic criteria for predicting vertebral fracture in breast cancer patients with skeletal metastasis. (Clin Cancer Res 2009;15(24):7676-83)