# The Role of [18F]FDG PET/CT Prior to and During Neoadjuvant Chemotherapy for Soft Tissue Sarcomas

## TL;DR

This study shows that [18F]FDG PET/CT scans can help predict treatment response and disease recurrence in soft tissue sarcoma patients undergoing chemotherapy.

## Contribution

The study identifies specific PET parameters that correlate with pathological response and recurrence-free survival in soft tissue sarcoma patients.

## Key findings

- Higher baseline MTVBL, TLGBL, and ΔSUVmax values are associated with better pathological response in soft tissue sarcoma patients.
- Changes in PET parameters like ΔSUVmax, ΔMTV, and ΔTLG are linked to increased fibrosis/hyalinization after chemotherapy.
- Baseline MTVBL, TLGBL, and ΔMTV values above cutoffs are predictive of disease recurrence.

## Abstract

This retrospective, single-center study investigates the association between PET parameters and pathological response or disease recurrence in patients with soft tissue sarcoma (STS) treated with neoadjuvant chemotherapy (NACT). The maximum standardized uptake value (SUVmaxBL), metabolic tumor volume (MTVBL), and total lesion glycolysis (TLGBL) were measured at baseline [18F]FDG PET/CT and the change in percentage (ΔSUVmax, ΔMTV, ΔTLG) from baseline to early evaluation [18F]FDG PET/CT was calculated. The optimal cutoff values of the different PET parameters for pathological response, defined as <10% residual viable tumor (RVT) or >15% fibrosis/hyalinization, and recurrence-free survival were obtained for analysis. Forty-two patients who underwent baseline [18F]FDG PET/CT and NACT followed by surgery were included between January 2015 and January 2023. The primary diagnoses were angiosarcoma (n = 15), leiomyosarcoma (n = 15), sarcoma not otherwise specified (n = 9) and synovial sarcoma (n = 3). Twenty-eight (66.6%) patients underwent an early evaluation PET/CT. MTVBL, TLGBL, and ΔSUVmax (p = 0.024; p = 0.042, p = 0.009, respectively) values above the cutoff were associated with a pathological response based on RVT. ΔSUVmax, ΔMTV, and ΔTLG (p = 0.002; p = 0.019; p = 0.039, respectively) values above the cutoff were positively related to >15% fibrosis/hyalinization. MTVBL, TLGBL, and ΔMTV (p = 0.014; p = 0.022; p = 0.034, respectively) values above the cutoff were prognostic for the recurrence of disease. [18F]FDG PET/CT has a promising role in STS patients treated with NACT.