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IELSG37 showed that people with primary mediastinal B-cell lymphoma whose scan is clear after chemotherapy do not need radiotherapy to the chest, sparing young patients decades of heart and breast cancer risk.
IELSG37 registered 545 patients with primary mediastinal large B-cell lymphoma treated with rituximab-containing immunochemotherapy (mostly R-CHOP or dose-adjusted EPOCH-R, by centre) and randomised the 268 who reached a complete metabolic response on end-of-treatment PET (Deauville 1 to 3) to 30 Gy consolidation radiotherapy or to observation.
Progression-free survival at 30 months was 96.7 percent without radiotherapy and 98.5 percent with it, within the non-inferiority margin, with no difference in overall survival. Patients with residual PET uptake were not randomised and received radiotherapy, in whom outcomes were also good.
The trial settled a forty-year argument: mediastinal radiotherapy can be omitted in the majority of patients who reach complete metabolic response, and PET now decides who is irradiated.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
545 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival at 30 monthsprimary | Observation | 132 | 96.7% | - | - | link |
| Consolidation radiotherapy 30 Gy | 136 | 98.5% |
Shares Deauville five-point scale, Lugano classification / Ann Arbor staging, R-CHOP (lymphoma chemoimmunotherapy), FDG PET.
Shares IELSG37: omission of radiotherapy in primary mediastinal B-cell lymphoma after a negative PET scan, PET-adapted (response-adapted) therapy, Lugano classification / Ann Arbor staging, FDG PET.
Shares R-CHOP (lymphoma chemoimmunotherapy), FDG PET, Primary mediastinal (thymic) large B-cell lymphoma, Rituximab.
Shares Lugano classification / Ann Arbor staging, FDG PET, Rituximab, IMRT / IGRT (modern external beam).
Shares Primary mediastinal (thymic) large B-cell lymphoma, Rituximab.
Shares R-CHOP (lymphoma chemoimmunotherapy), FDG PET, Rituximab.
Shares PET-adapted (response-adapted) therapy, Deauville five-point scale, FDG PET.