An interventional study of observation and 3D-Conformal Radiotherapy (3D-CRT) in Primary Mediastinal B-cell Lymphoma, sponsored by International Extranodal Lymphoma Study Group (IELSG). Active, not recruiting at 85 sites in 14 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-01-15.
Sponsored by International Extranodal Lymphoma Study Group (IELSG) · Not applicable, Interventional, and Treatment
Primary mediastinal large B cell lymphoma is treated with a combination of chemotherapy and the monoclonal antibody rituximab (chemoimmunotherapy).
Following chemoimmunotherapy patients receive radiation therapy if they have residues which may be active tumour. However at the end of chemoimmunotherapy the majority of patients show tissue scarring that is not necessarily active tumor. In recent years, PET/CT has proved to be a good tool to accurately identify active tumor from scar tissue in patients treated for mediastinal lymphoma.The purpose of this trial is to test whether radiation therapy is really necessary in patients where PET/CT has shown that the tumor is no longer active. Therefore we will compare radiation treatment with careful observation.
Patients that at the end of conventional treatment of chemoimmunotherapy have a negative PET/CT (i.e., without residues suspected to contain active tumor), will randomly assigned to two different treatment groups: one treatment group will receive the radiation treatment, and the other treatment group will receive careful observation.
The trial is planned according to a non-inferiority design aimed at demonstrating that progression free survival after the experimental treatment (observation) is not worse than after the standard comparator (mediastinal irradiation.Participation in this study could spare patients with complete remission at the end of chemo immunotherapy (PET/CT negative) radiation therapy that may be unnecessary.
International Extranodal Lymphoma Study Group (IELSG) is the lead sponsor of 29 studies on the registry; 4 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Follow up visits are scheduled from randomization. Patients will be seen at 3-months intervals for 24 months, then every 6 months until 5 years from randomization.
Other: observation
Radiotherapy will be delivered in this phase III protocol, as alternative to observation, as consolidation treatment in patients achieving a CR status (PET/CT scan negative) at the end of R-chemotherapy, with a total dose of 30 Gy.
Radiation: 3D-Conformal Radiotherapy (3D-CRT)
observation
Radiation treatment should start within 6-8 weeks after the end of chemotherapy.
Progression free survival (PFS)
The primary outcome endpoint will be Progression Free Survival (PFS) in patients PET-negative after R-chemotherapy. Failure events for PFS are progression (defined as an increase in size of existing masses or the development of new sites of disease using the same radiological investigations CT or PET/CT and/or MRI - as for the pre-chemotherapy assessment) or death from any cause.
Time frame: 30 months from the randomization
Overall survival (OS)
OS is defined as the time from registration until death as a result of any cause until five years from registration
Time frame: 5 years from registration
Long term toxicity
Reporting of any adverse event which is judged in the opinion of investigator to be possibly treatment-related up to 10 years from randomization (including all cardiac and pulmonary events, relapses and second cancers and deaths)
Time frame: 10 years from registration
This study is active, not recruiting, as verified in Jan 2026. You cannot join it, but the record below documents what was studied.
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International Extranodal Lymphoma Study Group (IELSG)