Early Evidence Suggests Proton Therapy Offers Safe, Long-Term Treatment for Hodgkin Lymphoma

Despite some success in treating patients with Hodgkin lymphoma, many patients suffer from late effects of radiation therapy and chemotherapy treatment, including the possible onset of breast cancer or heart disease.   A study by the University of Florida Proton Therapy Institute shows that the use of proton therapy following chemotherapy in patients with Hodgkin lymphoma has a success rate similar to the conventional treatments with a reduction of radiation outside of the target area, or “involved-node”, potentially reducing the risk of late effects caused by radiation.

The phase II study published in the online edition of the International Journal of Radiation Oncology Biology Physics, “Involved-Node Proton Therapy in Combined-Modality Therapy for Hodgkin Lymphoma,” continues to add to the mounting evidence supporting the use of proton radiation therapy for positive long-term treatment outcomes. Several retrospective dosimetry studies, measuring the radiation dose in tissue resulting from exposure to direct and/or indirect radiation, have reported the advantages of proton therapy in Hodgkin lymphoma as a way of reducing the radiation dose to the organs at risk, such as the heart, breast and lungs. However, this study is the first of its kind to track the results of proton therapy treatment on patients with Hodgkin lymphoma.

The study tracked 15 patients between September 2009 and June 2013 with newly diagnosed Hodgkin lymphoma as they received involved-node proton therapy (INPT), which specifically targets initially involved lymph node(s) containing the Hodgkin lymphoma, after completing chemotherapy. Further, the study evaluated the radiation dose in the surrounding healthy tissue as a result of proton therapy compared with conventional treatments, called intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3DCRT).

The data shows a three-year relapse-free rate of 93 percent and a three-year event-free rate of 87 percent. In addition, no patients developed grade three or higher toxicity during follow-up.

“All 15 patients derived benefits from using proton therapy. The results show that the use of protons, as opposed to similar conventional photon therapy, reduced the risk of long-term side effects by reducing or eliminating radiation doses to healthy tissue without compromising the cure rate,” said lead researcher Bradford S. Hoppe, M.D., radiation oncologist at the UF Proton Therapy Institute and assistant professor in the University of Florida College of Medicine department of radiation oncology.

“Three years after the National Comprehensive Cancer Network guidelines endorsed the use of proton therapy, this study reinforces proton therapy as a safe alternative to the more conventional forms of radiation,” Hoppe said.