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necessary in patients where PET/CT has shown that the tumor is no longer active.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.