PET positivity – the agony of choice: response assessment and interpretation of increased FDG uptake of residual mediastinal tissue after frontline therapy in Hodgkin lymphoma.

What is it that we actually see when looking at PET (positron emission tomography)-positive signals in Hodgkin lymphoma (HL)? Thus, the question of how to manage PET-positive lesions at the end of frontline therapy in HL is indeed crucial, because undertreating a disease that can be cured with firstline treatment in 80-90% of cases must definitely be avoided. As a result the authors concluded that it may not always be decisive to perform a biopsy for PET-positive residual mediastinal tissue after frontline therapy and that it was safe and appropriate to first closely observe asymptomatic patients instead of directly intensifying treatment. In the GHSG HD15 trial Engert et al. assessed whether administering RT only to patients with persistent PET-positive residues after chemotherapy was justifiable compared to earlier trials where irradiation was given to all initial bulky findings and all residual disease. [Extracted from the article]