Patients experience more severe side effects with x-ray radiation therapy than proton therapy

Severe side effects are less likely for patients receiving proton therapy than those receiving traditional x-ray radiation therapy, according to research to be presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

The study was a collaboration between researchers from Washington University School of Medicine in St. Louis and the Perelman School of Medicine at the University of Pennsylvania (Penn Med) in Philadelphia.

The team analyzed data from nearly 1,500 patients who received combined chemotherapy and radiation therapy for a variety of cancers that had not yet spread to other parts of the body. While 11.5% of patients in the proton therapy group experienced a severe side effect—one requiring hospitalization—within 90 days, 27.6% of patients in the x-ray radiation therapy group reported such a side effect.

“Proton therapy was associated with a substantial reduction in the rates of severe acute side effects—those that cause unplanned hospitalizations or trips to the emergency room—compared with conventional photon, or x-ray, radiation for patients treated with concurrent radiation and chemotherapy,” first author Brian C. Baumann, MD, an assistant professor of radiation oncology at Washington University and an adjunct assistant professor of radiation oncology at Penn Med, said in a news release. “The opportunity to reduce the risk of severe side effects for patients and thereby improve their quality of life is very exciting to me. While there have been other studies suggesting that proton therapy may have fewer side effects, we were somewhat surprised by the large magnitude of the benefit.”

The researchers also found “no differences between the two groups in survival,” according to the news release. Overall survival after one year was 83% for the proton therapy group and 81% for the x-ray radiation therapy group.

Though costs were not a focus of this particular study, the authors plan on exploring that aspect of this issue more closely in the future.

The 2019 ASCO Annual Meeting takes place May 31-June 4, 2019.