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Poor predictive value of positive interim FDG-PET/CT in primary mediastinal large B-cell lymphoma
Julien Lazarovici1, Marie Terroir2, Julia Arfi-Rouche3
1Department of Hematology, Gustave Roussy and Université Paris Saclay, 114 Rue Edouard Vaillant, 94805, Villejuif, France.
Purpose:
Though commonly used to assess response to therapy, the prognostic value of interim FDG-PET/CT in Primary Mediastinal Large B-cell Lymphoma (PMBCL) is unclear.
Methods:
We conducted a retrospective study on 36 consecutive patients treated at our institution for a PMBCL between 2006 and 2014. All patients with a positive interim FDG-PET/CT had undergone histological restaging consisting either in a surgical debulking of the residual lesion (15 patients) or a CT-guided core needle biopsy (two patients). All FDG-PET/CT were secondarily reviewed according to the more recent Deauville criteria.
Results:
Interim FDG-PET/CT was considered positive in 17/36 patients using visual evaluation. Among these patients, 14 had a Deauville score of 4. Histological restaging was negative in all but one case, showing inflammation and/or fibrosis. After a median follow-up of 48.5 months, a total of five patients have relapsed, two patients in the positive FDG-PET/CT group, and three patients in the negative FDG-PET/CT group, respectively.
Conclusions:
These data indicate that a positive interim FDG-PET/CT does not reflect persistence of active disease in the vast majority of PMBCL cases. The relapse rate appears similar regardless of interim FDG-PET/CT results and interpretation criteria. This suggests that interim FDG-PET/CT has a poor positive predictive value, thus kt should be used with caution in PMBCL.
Insights
A positive interim FDG-PET/CT scan in Primary Mediastinal Large B-cell Lymphoma (PMBCL) often indicates inflammation, not active disease. Relapse rates are similar regardless of scan results, suggesting caution when interpreting these scans.
Area of Science:
- Oncology
- Nuclear Medicine
- Radiology
Background:
- Primary Mediastinal Large B-cell Lymphoma (PMBCL) is an aggressive non-Hodgkin lymphoma.
- Interim Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) is used to assess treatment response.
- The prognostic significance of interim FDG-PET/CT in PMBCL remains uncertain.
Purpose of the Study:
- To evaluate the prognostic value of interim FDG-PET/CT in patients with PMBCL.
- To determine if a positive interim FDG-PET/CT accurately predicts treatment failure or disease persistence.
Main Methods:
- Retrospective analysis of 36 consecutive PMBCL patients treated between 2006 and 2014.
- Interim FDG-PET/CT scans reviewed using Deauville criteria.
- Histological restaging performed for patients with positive interim scans.
Main Results:
- 17 out of 36 patients had a positive interim FDG-PET/CT (visual evaluation).
- 14 of these positive scans were Deauville score 4.
- Histological restaging was negative in most cases (inflammation/fibrosis).
- Relapse rates were similar in both positive (2/17) and negative (3/19) interim FDG-PET/CT groups.
Conclusions:
- A positive interim FDG-PET/CT in PMBCL often reflects residual inflammation or fibrosis, not active disease.
- Interim FDG-PET/CT has a poor positive predictive value in PMBCL.
- Results suggest caution in using interim FDG-PET/CT for treatment decisions in PMBCL.
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