Proton therapy for lung cancer patients spares their hearts from cardiac damage due to radiation exposure
Proton therapy reduces risk of heart disease for lung cancer patients
October 27, 2020
by John R. Fischer
, Senior Reporter
Lung cancer patients treated with proton therapy have less of a risk of incurring certain forms of heart disease than those treated with photon therapy.
That’s what researchers at Penn Medicine said in a presentation last weekend at the American Society for Radiation Oncology virtual Annual Meeting, claiming that they observed fewer mini-strokes and heart attacks in such patients as part of a retrospective trial. They claim it is the first study to suggest that proton therapy is more beneficial than intensity modulated radiotherapy in reducing cardiac dose effects.
"This shows us another potential benefit of proton therapy for lung cancer patients," said Dr. Timothy Kegelman, M.D., chief resident in the department of radiation oncology in the Perelman School of Medicine at the University of Pennsylvania, in a statement. "We know proton has the ability to minimize radiation doses to surrounding organs like the heart. And these latest findings suggest that sparing correlates with fewer cardiac problems, compared to conventional therapy."
With proton therapy, users can target tumors more precisely and spare normal surrounding tissues and organs, such as the heart, to radiation, thereby decreasing the risk of cardiac toxicity.
The Penn Medicine study was composed of more than 200 patients. Of this, 1.1% with locally advanced non-small cell lung cancer who were treated with proton therapy experienced post-treatment mini-strokes (transient ischemic attacks) after a median follow up of 29 months. This was much less than the 8.2% treated with photon radiation therapy who experienced the same problem. In addition, 2.3% of proton patients experienced myocardial infarctions compared to 9% of photon patients, though the difference was not statistically significant, say the authors.
"While these findings are promising and add to growing evidence, more research and the results of the randomized trial will help us better determine and understand how treating with protons may reduce cardiac event risk," Kegelman said.
No differences were found in the number of cases for atrial fibrillation, coronary artery disease, heart failure or stroke. The researchers are continuing to investigate the effects of both forms of therapy for these issues by examining the severity of the cardiac events and radiation dose to specific parts of the heart.
They also are taking part in a large, prospective, international phase III clinical trial evaluating the difference between proton therapy and photon therapy in lung cancer patients. The study has been underway since 2014 and is expected to show that protons reduce cardiac-related morbidity and mortality, thereby leading to a higher cure rate. Patient recruitment is expected to be completed by 2022.