Hodgkin Lymphoma patients with limited stage are commonly cured with limited chemotherapy followed by radiotherapy. Studies have shown a risk of late toxicity from the radiotherapy, such as second cancer, heart failure and lung toxicity. With proton therapy the dose to normal tissue can be minimised without compromising the dose to the tumor. The aim of our study is to investigate whether proton therapy can be delivered in a safe way to Hodgkin Lymphoma patients with less late side effects than conventional radiotherapy, while retaining the high cure rate.

This is a multicentre phase II study of PBS proton beam therapy in patients ≤60 years, with early stage Hodgkin Lymphoma treated with induction chemotherapy. The study is performed in a non-inferiority setting comparing with a historical population-based consecutive Swedish material. The control group was treated according to the same principles, except that the radiotherapy was delivered with photons.

Inclusion Criteria:

• Histological diagnosis of classic Hodgkin Lymphoma.
• Ann Arbour stage 1A, 1B or 2A.
• Both patients with and without risk factors, i.e. bulky disease, erythrocyte sedimentation rate (ESR)>50, more than two involved sites.
• Supra diaphragmal disease.
• Age 18-60 years.
• Eastern Cooperative Oncology Group (ECOG) performance status 0 - 2.
• Initial staging positron emission tomography/computed tomography (PET/CT).
• Induction chemotherapy including 2 cycles of ABVD for patients without risk factors and 4 cycles of ABVD for patients with risk factors.
• For patients with risk factors a CT after 2 ABVD confirming complete remission (CR) or partial remission (PR). For patients without risk factors clinical response is sufficient at inclusion, but a CT scan is recommended before start of radiotherapy.
• Radiotherapy (RT) start not later than 6 weeks after end of chemotherapy.
• Written informed consent obtained prior to any study specific procedures.
• Women of reproductive age must agree to use contraceptives during the study treatment period.

Exclusion Criteria:

• Pregnancy.
• Serious concomitant systemic disorder endangering treatment delivery.
• More than 5mm tumour motion on 4 dimensional computed tomography (4DCT) unless deep inspiration breath hold (DIBH) is used. Not applicable if target is located outside mediastinum or photon treatment is planned.
• Clinical or radiographic stable disease (SD)/ progressive disease (PD) during induction chemotherapy.
• Not able to comply with treatment and study procedures.
• No additional active malignancy except indolent lymphoma in the bone marrow, basal cell carcinoma of the skin, squamous cell carcinoma of the skin or in situ cervical cancer.