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Persistent Fluorodeoxyglucose Uptake on Post-Definitive Radiotherapy PET/CT Evaluation Predicts Poor Survival in
Badira Cheriyalinkal Parambil1, Sneha Shah2, Nilendu Purandare2
1Department of Pediatric Oncology, Tata Memorial Hospital, Homi Bhabha National Institute (HBNI), Mumbai, Maharashtra, India.
Cancer Medicine
|June 6, 2026
Summary
Residual FDG-avid disease on post-treatment PET/CT scans in Ewing Sarcoma (ES) patients indicates a poor prognosis. A high SUVmax value on these scans identifies an ultra-high-risk group needing closer monitoring.
Area of Science:
- Oncology
- Radiotherapy
- Nuclear Medicine
Background:
- 18F-FDG-PET/CT is standard for Ewing Sarcoma (ES) staging.
- Its prognostic value for residual masses after radiotherapy is unclear.
Purpose of the Study:
- To assess the prognostic significance of residual masses on 18F-FDG-PET/CT after definitive radiotherapy in pediatric ES patients.
Main Methods:
- Retrospective analysis of pediatric ES patients (≤15 years) treated with radiotherapy.
- 18F-FDG-PET/CT (PET-3) performed 3 months post-radiotherapy.
- Classification of residual disease: no residual, anatomic residual (no FDG-avidity), or FDG-avid residual.
Main Results:
- 149 patients analyzed; 46.3% had metastatic disease.
- PET-3 showed FDG-avid residual in 17.4%, anatomic residual in 30.2%, and no residual in 52.3%.
- Five-year event-free survival (EFS) was significantly lower with FDG-avid residual (42.6%) compared to no residual (52.8%).
- In metastatic cases with FDG-avid residual, 5-year EFS was 22.9% vs. 75.0% in localized disease.
- PET-3 SUVmax > 3.9 was prognostic for EFS in metastatic ES (HR=9.59, p≤0.001).
Conclusions:
- Persistent FDG-avid residual disease post-radiotherapy in metastatic ES signifies a poor prognosis.
- A PET-3 SUVmax > 3.9 identifies an ultra-high-risk cohort requiring intensified management.
