RecruitingPhase 3Radiation therapyBrentuximab Vedotin in Early Stage Hodgkin LymphomaRADAR is a multicentre, international, randomised, open-label phase III clinical trial composed of 2 trials running in parallel. Trial 1 will be led and sponsored by University College London (UCL) and conducted in Europe and Australia/New Zealand. Trial 2 will be led by the Canadian Cancer Trials Group (CCTG) and conducted in North America, with CCTG the regulatory sponsor in Canada, and University of Miami the regulatory sponsor and IND holder in the US. Datasets from Trial 1 and Trial 2 will be combined to achieve the total sample size. Data analysis will be performed by UCL and therefore UCL is responsible for the clinicaltrials.gov entry. Eligible patients will be randomised to receive either ABVD or A2VD chemotherapy. An interim PET-CT scan will be performed after 2 cycles of treatment, which will be used to adapt subsequent treatment. Patients will receive a total of 3-4 cycles of chemotherapy and may also receive involved site radiotherapy as consolidation. Patients will be followed up for a minimum of 5 years after treatment.