Can FDG-PET assess the response to chemotherapy and predict tissue necrosis in osteosarcoma and Ewing sarcoma?

Abstract

Introduction: Osteosarcoma (OS) and Ewing sarcoma (ES) represent the pediatric population’s most common malignant bone tumors. 18-Fluorodeoxyglucose positron emission tomography has been shown to be effective in both the diagnostic and staging phases of cancer treatment. In recent years, some studies have also explored the possibility that FDG-PET could have a prognostic role. Aim: Our research aimed to evaluate if maximum standardized uptake value (SUVmax) variations after chemotherapy could be correlated with tissue necrosis and be linked with patients’ survival rates. Materials and methods: This observational retrospective study included all cases treated for skeletal OS or ES in our institution between 2006 and 2018. We recorded patients’ SUVmax values before and after chemotherapy, the necrosis grade (for those who received surgery), and survivorship. Forty-one cases (17 OS and 24 ES) were included. Among the 36 cases that received surgery, 15 were responders, and 20 were non-responders. Results: Our data suggested a statistically significant correlation between tumor necrosis and differential SUVmax after neoadjuvant treatment (p=0.007). In particular, cases with differential SUVmax higher than 4.7 or a variation higher than 63% had better oncological outcomes. Conclusion: Our study testifies to the effectiveness of FDG-PET in predicting tissue necrosis on ES and OS, thereby representing a promising prognostic factor.