18f-FDG-PET imaging as an early survival predictor in patients with high-grade soft tissue sarcomas undergoing neoadjuvant therapy.

Abstract

10012 Background: Neoadjuvant therapy is associated with considerable toxicity and limited survival benefits in patients with soft tissue sarcoma (STS). We prospectively evaluated whether 18F-FDG PET/CT (PET) imaging after the initial cycle and after end of neoadjuvant therapy could predict overall survival in these patients. Methods: 76 patients (primary STS: n=57; metastatic disease: n=19) with high grade STS were included in this study. PET was performed prior to (n=76), after one cycle (n=52) and after the end of neoadjuvant therapy (n=74). Overall survival was correlated with changes of SUVpeak, RECIST, histopathological response and other parameters predictive of STS survival. Results: One-, two- and five- year survival rates were 95±3.0%, 86±4.6% and 68±6.6% for primary STS. Corresponding one- and two- year survival rates for recurrent/metastatic STS were 77±10.0% and 47±12.1%. Optimal cut-off for early decreases in SUV peak were significant predictors of survival in log-rank test (p=0.027 and p=0.043). However, late decreases in SUV peak were only predictive in primary STS (SUV peak decrease 57%; p=0.035) but not in recurrent/metastatic STS (SUV peak decrease 52%; p=0.057). In primary STS, 7/15 early PET non-responders but only 4/24 early PET responders died during follow up (p=0.068). Conclusions: 18F-FDG-PET seems feasible to predict survival after the initial cycle of neoadjuvant chemotherapy in both patients with primary STS and recurrent/metastatic STS and can potentially serve as an intermediate endpoint biomarker in clinical research and patient care.