PET/CT allows stratification of responders to neoadjuvant chemotherapy for high-grade sarcoma: a prospective study.

PURPOSE: The aim of the present study was to determine whether metabolic reduction is capable of reflecting the histopathologic response and outcome after neoadjuvant chemotherapy in patients with high-grade sarcoma. PATIENTS AND METHODS: Forty-two patients with histologically proven high-grade sarcoma underwent neoadjuvant chemotherapy followed by surgical resection. Quantitative F-18 fluorodeoxyglucose (F-18-FDG) positron emission tomography (PET)/computed tomography scans were acquired before and after the first cycle and after completion of neoadjuvant chemotherapy. Standardized uptake values (SUVs) and metabolic reduction rates were compared with histopathologic response, progression-free survival, and overall survival. RESULTS: Baseline SUVmax was 10.9 ± 3.6 (range, 3.8-19.6). Therapeutic effect resulted in 10 patients (24%) with a satisfactory response and in 32 patients (76%) with an unsatisfactory response after completion of neoadjuvant chemotherapy. The SUV decreased to 7.8 ± 3.4 after the first cycle (t1) of chemotherapy and to 5.2 ± 3.4 after completion (t2) of chemotherapy. Histopathologic response and percentage SUV (t2) reduction rate were independent predictors of progression-free survival and overall survival in the multivariate analyses. CONCLUSION: Metabolic reduction after neoadjuvant chemotherapy evaluated by F-18 FDG PET or computed tomography can be used for stratification of the histopathologic response in patients with high-grade sarcoma.