Cardiac events were relatively common following high-dose thoracic radiotherapy among patients with stage III non-small cell lung cancer (NSCLC) treated between 1996 and 2009, according to a study published in the Journal of Clinical Oncology.1
Although the Radiation Therapy Oncology Group (RTOG) 0617 study demonstrated that higher doses of radiotherapy to the heart were associated with worse overall survival among patients with stage III NSCLC, the significance of radiotherapy-associated cardiotoxicity in this setting remains unclear.
To evaluate the impact of heart dose among patients treated for stage III NSCLC, investigators analyzed data from 112 patients who received dose-escalated radiotherapy of 70 to 90 Gy in 6 clinical trials conducted at the University of North Carolina’s Lineberger Comprehensive Cancer Center in Chapel Hill.
After a median follow-up of 8.8 years, among surviving patients, 23% experienced at least 1 cardiac event, defined as symptomatic pericardial effusion, acute coronary syndrome, pericarditis, significant arrhythmia, or heart failure. Median time to first cardiac event was 26 months.
Twelve patients developed an arrhythmia, 7 had effusion, 5 experienced a myocardial infarction, 3 had unstable angina, 2 had pericarditis, and 1 developed heart failure.
Each 1 Gy increase in mean heart dose significantly increased the risk of a cardiac event by 3% (hazard ratio, 1.03; P = .002). Coronary artery disease (P < .001) and WHO/International Society of Hypertension score (P = .04) were significantly associated events.
Heart doses were not, however, associated with overall survival.
With respect to heart mean dose, 4%, 7%, and 21% of patients who received less than 10 Gy, 10 to 20 Gy, or 20 Gy or more developed a cardiac event by 2 years, respectively.
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The findings suggest that radiotherapy-associated cardiotoxicity following treatment of stage III NSCLC may occur earlier than previously reported. Clinicians should minimize heart doses in this population.
- 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. J Clin Oncol. 2017 Jan 23. doi: 10.1200/JCO.2016.70.0229 [Epub ahead of print]