Could Lung-Cancer Radiation Therapy Increase Heart Risk?

Radiation therapy is associated with a dose-dependent increased risk of cardiac events in patients with stage III lung cancer, according to the results of a recent study.

Previous research has indicated that higher heart doses of radiation in patients with stage III non-small cell lung cancer (NSCLC) is associated with worse overall survival. However, whether this is attributed to radiotherapy-associated cardiac injury is unclear.
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For their study, researchers analyzed data from 112 patients with stage III NSCLC who received dose-escalated radiation therapy to 70 to 90 Gy in six trials. The researchers reviewed the patients’ radiation therapy plans and cardiac doses, as well as their cardiac risk, which was assessed with the WHO/International Society of Hypertension score. 

Overall, 26 patients (23%) experienced one or more events at a median of 26 months to first event, including myocardial infarction, unstable angina, pericarditis, arrhythmia, and heart failure. Heart doses coronary artery disease, and WHO/International Society of Hypertension score were all associated with a higher risk of events, and heart doses remained significant following multivariable analysis accounting for baseline risk. The 2-year competing risk–adjusted event rates for patients with heart mean dose <10 Gy, 10 to 20 Gy, or ≥20 Gy were 4%, 7%, and 21%, respectively.

“Cardiac events were relatively common after high-dose thoracic [radiation therapy] and were independently associated with both heart dose and baseline cardiac risk. [Radiation therapy]-associated cardiac toxicity after treatment of stage III NSCLC may occur earlier than historically understood, and heart doses should be minimized,” the researchers concluded.

—Michael Potts

Reference:

Wang K, Eblan MJ, Deal AM, et al. Cardiac toxicity after radiotherapy for stage III non–small-cell lung cancer: pooled analysis of dose-escalation trials delivering 70 to 90 Gy [published online May 2017]. J Clin Oncol.  doi: 10.1200/JCO.2016.70.0229.