The RADAR trial is a large phase III research study looking at the best way to treat people who have early stage Hodgkin Lymphoma (HL) and who have not had treatment before.

Doctors want to find out whether replacing one drug in the standard chemotherapy (called bleomycin) with a newer drug (called brentuximab vedotin) can:

• Help stop Hodgkin Lymphoma from coming back
• Help more people reach a deep remission more quickly
• Improve overall survival
• Reduce the risk of lung damage
• Reduce the number of patients who need radiotherapy
• Lower the chances of radiotherapy‑related side effects, such as heart problems or future cancers

Right now, the usual treatment for early stage Hodgkin Lymphoma is 3–4 cycles of ABVD chemotherapy (doxorubicin, bleomycin, vinblastine, dacarbazine), and many patients then have radiotherapy.

However, bleomycin can cause lung damage, so researchers are looking for safer alternatives.

Brentuximab vedotin (BV) is a targeted treatment. It works by attaching to lymphoma cells and delivering a drug directly into them to kill them. It is already used to treat people with relapsed or more advanced HL, and this study will test whether it is also effective for early stage HL.

Patients in the trial will be randomly assigned (like flipping a coin) to one of two treatment groups:

1. ABVD

   • The current standard treatment
   • Includes bleomycin

2. A2VD

   • An experimental treatment
   • Bleomycin is replaced with brentuximab vedotin

RADAR uses a PET‑response adapted design, meaning treatment is adjusted based on how your lymphoma responds early on.

• After 2 cycles, you will have a PET‑CT scan.
• A specialist team will review your scan.

If the scan shows a good response:

• You will have one more cycle of ABVD or A2VD (depending on your group).

If the response is less good:

• You will have two more cycles of ABVD or A2VD,
• Followed by radiotherapy.

Patients will be followed up for at least 5 years to check how they are doing and to monitor any side effects or late effects.

If you wish, you can also take part in optional additional studies, including:

• A PET‑CT scan after your first cycle of treatment
• Providing extra blood samples or tumour samples for laboratory research

These optional parts help researchers better understand Hodgkin Lymphoma and how treatments work.