Lymphoma is most commonly treated with chemotherapy, and in some cases, radiotherapy is added to give the treatment the best possible chance of success. The radiation doses used for lymphoma are generally lower than for many other cancers, meaning the main benefit of proton beam therapy lies in reducing long-term side effects rather than improving tumour control.

This is particularly relevant for younger patients and for those with lymphoma affecting sensitive areas of the body. When radiotherapy is delivered to regions such as the chest or abdomen, nearby organs may be exposed to radiation, which can increase the risk of late complications many years after treatment.