FDG-positron emission tomography/computed tomography and new opportunities for risk stratification

Background To investigate the use of positron emission tomography/computed tomography with F-18-fluorodeoxyglucose (FDG-PET/CT) before, during, and after completion of chemotherapy, to optimize treatment intensity in Hodgkin lymphoma. Objectives FDG-PET/CT-adapted therapy concepts have been tested by the German Hodgkin Study Group (GHSG) in the multicenter studies HD15, HD16, HD17 and HD18. The HD15 trial investigated the omission of radiotherapy in FDG-PET/CT-negative residual tissue for advanced stages. The HD16 trial investigated a similar question for early stages, and the HD17 trial investigated intermediate stages. HD18 evaluated the possibility of reducing the number of chemotherapy cycles in PET-negative patients after 2 cycles of chemotherapy. Across stages, data from HD16, HD17, and HD18 were used to analyze the use of FDG-PET/CT in initial staging. Results Therapy stratification by FDG-PET/CT after completion of chemotherapy is safe in advanced stages of Hodgkin lymphoma as well as in intermediate stages. Also, FDG-PET/CT after 2 cycles of chemotherapy in advanced stages allows a reduction in the number of chemotherapy cycles. FDG-PET/CT is now the standard of care for staging prior to therapy initiation, not least because it allows bone marrow biopsy to be omitted. In contrast, omission of radiotherapy after less intensive chemotherapy in early stages of Hodgkin lymphoma has not become standard. Conclusion FDG-PET/CT is standard in staging before, during, and after chemotherapy of Hodgkin lymphoma.