The Value of Baseline [18F]FDG-PET in Predicting the Progression-Free Survival in Patients with Thymic Epithelial Tumours: A Systematic Review and Meta-Analysis

TL;DR

This study finds that baseline [18F]FDG-PET parameters like SUVmax and SUVmean may predict survival outcomes in thymic epithelial tumor patients, but more research is needed.

Contribution

The study systematically evaluates and quantifies the prognostic value of [18F]FDG-PET parameters for progression-free survival in thymic epithelial tumors.

Findings

SUVmax as a continuous variable significantly predicts worse progression-free survival (HR: 1.18).

SUVmean also shows a significant association with impaired progression-free survival (HR: 1.41).

MTV and TLG do not show significant prognostic value due to limited data precision.

Abstract

Background/Objectives: [18F]FDG-PET is often used for staging thymic epithelial tumours (TETs). However, its prognostic role remains uncertain. The aim of this present systematic review and meta-analysis is to assess the prognostic value of baseline [18F]FDG-PET-derived semiquantitative parameters in predicting progression-free survival (PFS) in patients with TETs. Methods: A systematic review and meta-analysis were conducted according to PRISMA guidelines. PubMed, Embase, and Scopus databases were searched up to 30 May 2025. Studies evaluating the prognostic impact of [18F]FDG-PET parameters on PFS in TETs were included. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated. Results: Six retrospective studies involving 593 patients were included. Maximum standardized uptake value (SUVmax), analysed as a continuous variable in four studies, significantly predicted worse PFS (HR: 1.18, 95% CI: 1.08–1.29, p < 0.001), with high inter-study heterogeneity (I2 = 79.7%). When dichotomized (two studies), higher SUVmax was associated with significantly poorer PFS (HR: 9.00, 95% CI: 2.93–27.71). Similarly, mean SUV (SUVmean) as a continuous predictor was also significantly associated with impaired PFS (HR: 1.41, 95% CI: 1.25–1.59), but only two studies assessed this parameter. Conversely, metabolic tumour volume (MTV) and total lesion glycolysis (TLG), both assessed as continuous prognosticators, did not show a significant prognostic value. Notably, in both MTV and TLG analyses, two studies contributed a weight of 0%, reflecting limited precision and highlighting the need for larger data. Conclusions: Baseline [18F]FDG-PET parameters such as SUVmax and SUVmean showed a potential prognostic value in patients with TETs. However, these results are based on a limited number of retrospective studies with significant heterogeneity. Prospective multicentre investigations are necessary to confirm the potential role of [18F]FDG-PET for risk stratification in TETs.

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