Proton therapy reduces risk of severe side effects in cancer patients compared to radiation

Utilizing proton therapy can greatly lower the risk of severe side effects in patients with non-metastatic cancer compared to conventional radiation treatments, according to a recent study published in JAMA Oncology.

A group of researchers from the Perelman School of Medicine at the University of Pennsylvania called the analysis the largest review of its kind and the best information available on the topic. While cure rates between both groups of patient was strikingly similar, proton therapy reduced the relative risk of side effects potentially requiring hospitalization by two-thirds.

“This is exciting because it shows that proton therapy offers a way for us to reduce the serious side effects of chemo-radiation and improve patient health and well-being without sacrificing the effectiveness of the therapy,” Brian Baumann, MD, assistant professor of radiation oncology at Penn, said in a news release.

Photon radiation, in most cases, delivers radiation via multiple x-ray beams directly to the tumor target, but also deposits radiation in normal, healthy tissue. Proton therapy on the other hand, is an FDA-approved radiation alternative that directs positively charged protons to the tumor without leaving behind radiation in unintended areas of tissue.

Baumann and co-researchers examined grade-three side effects or higher—such as trouble breathing, difficulty swallowing, nausea or diarrhea, among others—after receiving either treatment. In total, 1,483 non-metastatic cancer patients were included—a majority (1,092) underwent traditional photon radiation.

The team judged their study on whether patients experienced adverse side effects within 90 days of treatment. Of those participants in the proton therapy group, 11.5% reported grade three side effects, compared to 27.6% of those in the traditional photon radiation cohort.

And a subsequent weighted analysis that controlled for other potential differences between the groups found proton patients faced a two-thirds lower relative risk of severe toxicity.

“We know from our clinical experience that proton therapy can have this benefit, but even we did not expect the effect to be this sizeable,” senior author James Metz, MD, leader of the Roberts Proton Therapy Center at Penn, said in the release.

Overall and disease-free survival were comparable between each group, suggesting proton therapy does not sacrifice the effectiveness of treatment.

An approach such as this, which limits potential negative side effects, may be particularly beneficial in older patients, Baumann et al. wrote.