# IELSG37: omission of radiotherapy in primary mediastinal B-cell lymphoma after a negative PET scan

Source: https://onco.cc/key-papers/paper-ielsg37-pmbcl-martelli-jco-2024/  
OnCo record `paper-ielsg37-pmbcl-martelli-jco-2024` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Patients with primary mediastinal B-cell lymphoma whose PET scan was negative after immunochemotherapy did just as well without consolidation radiotherapy as with it, so radiotherapy can safely be omitted for them.

## Summary

Phase 3 non-inferiority trial of 545 patients with primary mediastinal B-cell lymphoma treated with rituximab-containing immunochemotherapy; the 268 with a complete metabolic response on PET were randomised to observation or consolidation mediastinal radiotherapy.

Thirty-month progression-free survival was 96.2 percent with observation and 98.5 percent with radiotherapy, meeting non-inferiority, with overall survival of 99 percent in both arms.

## Fields

- Kind: Key paper
- Last checked: 2026-09-17
- Journal: Journal of Clinical Oncology
- Year: 2024
- DOI: 10.1200/JCO-24-01373
- Authors: Martelli M, Ceriani L, Ciccone G, et al.
- Findings: 30-month progression-free survival 96.2 percent (observation) vs 98.5 percent (radiotherapy); non-inferior.; Overall survival 99 percent in both arms.
- What it means: End-of-treatment PET now decides radiotherapy in primary mediastinal B-cell lymphoma: a negative scan means no radiotherapy, whichever chemotherapy regimen was used.
- Caveats: Patients with residual PET uptake were not randomised and mostly received radiotherapy.; Long-term second cancer data are pending.

## Sources

- J Clin Oncol 2024: https://doi.org/10.1200/JCO-24-01373
- PubMed: https://pubmed.ncbi.nlm.nih.gov/39159403/

## Connected records

- cancers: [Primary mediastinal (thymic) large B-cell lymphoma](https://onco.cc/cancers/primary-mediastinal-b-cell-lymphoma/)
- trials: [IELSG37](https://onco.cc/trials/ielsg37/)
- journals: [Journal of Clinical Oncology](https://onco.cc/journals/jco/)

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