TURIN, Italy, May 2 (UPI) -- Patients treated for non-small cell lung cancer using stereotactic body radiation therapy have an increased risk of death from causes other than cancer, according to researchers in the Netherlands.
Researchers at the Netherlands Cancer Institute found in a recent study that while SBRT treatment is targeted as closely as possible to hit only the tumor, it still can affect other organs, especially the heart.
SBRT delivers radiotherapy to a tumor by focusing on its location, the goal of which is to minimize exposing other organs to radiation. In doing so, however, researchers say this can result in higher doses reaching other organs.
In a presentation at the European Society for Radiotherapy and Oncology's annual meeting, researchers from the NCI said the risk is high for the heart because high doses of radiation damaging the left atrium and superior vena cava.
"Our results show that even within a few years a radiation dose to the heart is associated with an increased risk of non-cancer death for early stage lung cancer patients, and they indicate which regions of the heart possibly play a role," Dr. Barbara Stam, a researcher at the Netherlands Cancer Institute, said during a presentation at the conference.
For the study, published in the ESTRO 35 program, researchers analyzed data on 565 patients diagnosed with early NSCLC between 2006 and 2013 who were treated with SBRT.
During treatment and follow-up, the researchers devised a method to find how varying SBRT doses affected each part of the heart, combining the information with data on age, lung function and performance status.
After a mean follow-up time of 28 months, 58 percent of patients were alive. Although all radiation exposure to the heart increased the risk of non-cancer death, the researchers found specifically that patients receiving low doses of SBRT to the left atrium and low doses on the superior vena cava have a higher chance for survival than patients with high doses on either.
The study shows cancer treatment's effects on other organs need to be considered with each patient, Philip Poortmans, a professor at Radboud University Medical Center and president of ESTRO, said in a press release. The interaction between cancer treatment, comorbidity and the often advanced age of NSCLC patients must also be investigated further, he added.
Previous research with breast cancer patients suggests radiotherapy can affect the heart, but Stam said further research is needed to determine whether sparing the heart is possible. Potential changes to drug doses and regimens need to be explored, as well as whether changes would lower risk and increase survival from disease, she said.
"Validation and further investigations into the exact mechanisms and which heart structures are critical is warranted, but clinically, this could mean that patients might benefit from heart-sparing radiotherapy," Stam said.