INTRODUCTION
Pathological fractures in metastatic spinal tumors are known to adversely affect cancer treatment and shorten prognosis. Meanwhile, the maximum standardized uptake value (SUV max), a quantitative measure of FDG-PET uptake, has been reported to correlate with the occurrence of pathological fractures in metastatic bone tumors of the femur. However, it remains unclear whether SUV max is associated with the incidence of pathological fractures in metastatic spinal tumors. We investigated whether the SUVmax on FDG-PET could serve as a predictive factor for the occurrence of pathological fractures in metastatic spinal tumors from lung cancer.
METHODS
This study aimed to determine if SUV max measured by FDG-PET could serve as a predictive factor for pathological fractures. We included 39 patients (mean age 66.2 years, 25 men and 14 women) who had metastatic spinal tumors originating from primary lung cancer and underwent FDG-PET imaging at our hospital between 2016 and 2023. Demographic data, presence of bone-modifying agents, metastatic vertebral level, Spinal Instability Neoplastic Score (SINS), and SUV max of the metastatic vertebrae were evaluated. Pathological fractures occurring within one year of FDG-PET imaging were identified, and various assessment items were compared between the fracture and non-fracture groups. Logistic regression analysis was conducted with pathological fracture occurrence as the dependent variable to identify risk factors and calculate the cutoff value.
RESULTS
Among the 39 patients, there were 10 in the fracture group and 29 in the non-fracture group. The comparison between the two groups showed statistically significant differences in sex and SUV max (p=0.012, p<0.001), while other assessment items did not show significant differences. Logistic regression analysis using sex and SUV max as explanatory variables identified SUV max as an independent risk factor for pathological fractures (Odds ratio: 1.26, p=0.01). The cutoff value for SUV max was 12.9 (AUC=0.86, sensitivity: 0.80, specificity: 0.87).
DISCUSSION
SUV max was found to be a useful predictor of pathological fractures within one year. In contrast, the Spinal Instability Neoplastic Score (SINS), which has been reported as a predictor of pathological fractures in metastatic spinal tumors, did not successfully predict fractures in this study. SUV max may be valuable for assessing the risk of pathological fractures in metastatic spinal tumors at an early, less severe stage before significant instability occurs.