[18F]FDG PET/CT for evaluating early response to neoadjuvant chemotherapy in pediatric patients with sarcoma: a prospective single-center trial

Abstract

Introduction This is a prospective, single-center trial in pediatric patients with sarcoma aiming to evaluate [18F]FDG PET/CT as a tool for early response assessment to neoadjuvant chemotherapy (neo-CTX). Methods Bone or soft tissue sarcoma patients with (1) baseline [18F]FDG PET/CT within 4 weeks prior to the start of neo-CTX (PET1), (2) early interim [18F]FDG PET/CT (6 weeks after the start of neo-CTX (PET2), (3) evaluation of neo-CTX response by histology or MRI, and (4) definitive therapy after neo-CTX (surgery or radiation) were included. Semiquantitative PET parameters (SUVmax, SUVmean, SUVpeak, MTV and TLG) and their changes from PET1 to PET2 (ΔPET) were obtained. The primary endpoint was to evaluate the predictive value of PET1, PET2 and ΔPET parameters for overall survival (OS) and time to progression (TTP). The secondary outcome was to evaluate if [18F]FDG PET/CT can predict the response to neo-CTX assessed by histopathology or MRI. Primary and secondary outcomes were also evaluated in a subpopulation of patients with bone involvement only. Results Thirty-four consecutive patients were enrolled (10 females; 24 males; median age 15.1 years). 17/34 patients (50%) had osteosarcoma, 13/34 (38%) Ewing's sarcoma, 2/34 (6%) synovial sarcoma and 2/34 (6%) embryonal liver sarcoma. Median follow-up was 39 months (range 16–84). Eight of 34 patients (24%) died, 9/34 (27%) were alive with disease, and 17/34 (50%) had no evidence of residual/recurrent disease. Fifteen of 34 (44%) and 19/34 (56%) were responders and non-responders, respectively. PET2-parameters were associated with longer TTP (p < 0.02). ΔMTV was associated with tissue response to neo-CTX (p = 0.047). None of the PET1, PET2 or ΔPET parameters were associated with OS. Conclusion [18F]FDG PET/CT performed 6 weeks after the start of neo-CTX can serve as an early interim biomarker for TTP and pathologic response but not for OS in pediatric patients with sarcoma.

Prognostic value of fluorodeoxyglucose positron emission tomography derived metabolic parameters and textural features in pediatric sarcoma

“…Nevertheless, poor histologic response was significantly associated with lower PFS rates and shorter median PFS compared to the responder group in the Kaplan–Meier survival analysis, similar to the results of previous studies [13,17]. In previous studies, it was reported that the quantitative metabolic-volumetric FDG PET derived parameters were found to be significantly associated with histologic tumor response 13,17,19–21. These studies were generally based on the quantitative values of FDG PET imaging after NAC and the percentage changes between on baseline and post-therapy scans.…”

Radiologic Assessment of Osteosarcoma Lung Metastases: State of the Art and Recent Advances

“…Nevertheless, PET-CT has an established role in the detection of bone metastases with higher sensitivity compared to bone scans. Several studies suggest that PET may be a promising tool for response to therapy prediction in OS patients [ 72 , 73 ].…”