The management of Hodgkin and non-Hodgkin lymphoma is often with a combination of chemotherapy and radiation. Unfortunately, due to the young age at diagnosis and high cure rates, long-term side effects in lymphoma survivors from their initial treatment can present a problem. Often many oncologists will forgo the best curative therapy that includes radiation therapy, because of their concern about long-term side effects from radiation that can occur decades after treatment. The side effects that are most concerning are risk of subsequent cancers and cardiovascular problems including heart attacks and strokes.

Treating Hodgkin Lymphoma and Non-Hodgkin Lymphoma with Proton Therapy

Proton therapy can reduce the body dose of radiation by 40-50% compared with X-rays.

Modern radiation treatments in lymphoma use lower radiation doses, smaller radiation fields, and new radiation technology, such as proton therapy, which can reduce the body dose of radiation by 40-50% compared with X-rays. Proton therapy is an alternative form of radiation that is different from traditional high-energy X-ray radiation (or photons). Due to proton therapy’s unique properties, it can deliver the radiation dose to a specific depth in the body and then stop. X-ray radiation, on the other hand, continues to penetrate through normal tissue and organs (such as the lungs, heart, esophagus, breasts, and spinal cord), causing damage and toxicity.

Here are some CT images that illustrate radiation exposure for the same patient with a 3D Conformal Radiation Therapy (CRT) X-ray plan (left), an intensity-modulated X-ray radiotherapy (IMRT) plan (center), and a proton therapy plan (right). The top images are sagital cuts (side view), while the bottom are transverse images (crosswise view). The color wash represents high radiation doses in red, medium doses in yellow and green, and low doses in blue. As you can see, for this patient, the proton plan substantially reduces the radiation dose to the lung (the black area in the chest), heart (green), breasts, and stomach (orange). For this patient, proton therapy is expected to reduce the risk of breast cancer, lung cancer, stomach cancer, and heart problems.

What are the clinical results of using proton therapy in patients?

University of Florida Health Proton Therapy Institute has published outcomes on using proton therapy in Hodgkin lymphoma patients and in non Hodgkin lymphoma patients.^1,2  As expected, the cure rates are similar to those expected with X-ray therapy. The full benefits of using proton therapy rather than X-ray therapy are not expected to emerge until 10-20 years from now, when the late toxicities from radiation may develop including heart problems and radiation-induced cancers.

Massachusetts General Hospital (MGH), however, has published outcomes comparing proton patients treated at their hospital for various cancers compared with X-ray patients treated on a national cancer registry and demonstrated a 50% reduction in secondary cancers among patients getting proton therapy.³ This supports the use of proton therapy among lymphoma patients expected to live decades longer.

Which lymphoma patients benefit from proton therapy?

University of Florida Health Proton Therapy Institute conducted the first trial using proton therapy in Hodgkin lymphoma patients with involvement of the mediastinum (middle of the chest). In this study, proton therapy was able to reduce the radiation dose to all the organs at risk, including the heart, lung, breast, esophagus, and stomach compared with X-ray radiation. There was a benefit seen in using proton therapy in all patients enrolled in the study. Cure rates were similar to that seen with X-ray radiation.

In the coming decades, we expect to see survivors who have lower rates of heart problems and fewer radiation-induced cancers because proton therapy reduces the radiation dose to surrounding healthy organs.^1,4,5

Proton therapy has also been shown to reduce the radiation dose to critical organs for locations in the abdomen, pelvis, and head and neck region. ^6,7