In a Korean single-institution retrospective cohort study reported in JAMA Oncology, Kim et al found that higher sinoatrial node radiation doses were associated with an increased risk of atrial fibrillation and poorer survival in patients with limited-stage small cell lung cancer (SCLC) and locally advanced non–small cell lung cancer (NSCLC) who were receiving definitive chemoradiotherapy.
The study included 239 patients diagnosed with limited-stage SCLC and 321 diagnosed with locally advanced NSCLC between August 2008 and December 2019 at Yonsei Cancer Center, Seoul. They all were treated with definitive chemoradiotherapy.
At a median follow-up of 32.7 months (interquartile range = 22.1–56.6 months), 9 patients with SCLC and 17 with NSCLC had new-onset atrial fibrillation.
A higher maximum dose delivered to the sinoatrial node (SAN Dmax) was associated with a significantly increased risk of atrial fibrillation in patients with SCLC (≥ 53.5 Gy vs < 53.5 Gy; adjusted hazard ratio [HR] = 14.91, 95% confidence interval [CI] = 4.00–55.56, P < .001) and in patients with NSCLC (≥ 20.0 Gy vs < 20 Gy; adjusted HR = 15.67, 95% CI = 2.08–118.20, P = .008). SAN Dmax was not significantly associated with cardiac events other than atrial fibrillation.
Among patients with SCLC, the 3-year overall survival was 30.9% among those with SAN Dmax ≥ 53.5 Gy vs 48.5% among those with SAN Dmax < 53.5 Gy (P = .008). On a multivariate analysis, the adjusted hazard ratio for mortality was 2.68 (95% CI = 1.53–4.71, P < .001).
Among patients with NSCLC, the 3-year overall survival was 35.0% among those with SAN Dmax ≥ 20 Gy vs 54.5% among those with SAN Dmax < 20 Gy. On a multivariate analysis, the adjusted hazard ratio for mortality was 1.97 (95% CI = 1.45–2.68, P < .001).
The investigators concluded: “In this cohort study, results suggest that incidental irradiation of the sinoatrial node during chemoradiotherapy may be associated with the development of atrial fibrillation and increased mortality. This supports the need to minimize radiation dose exposure to the sinoatrial node during radiotherapy planning and to consider close follow-up for the early detection of atrial fibrillation in patients receiving thoracic irradiation.”
Seok-Min Kang, MD, PhD, of the Division of Cardiology, and Hong In Yoon, MD, PhD, of the Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, are the corresponding authors of the JAMA Oncology article.
Disclosure: The study was supported by the Severance Hospital Research Fund for Clinical Excellence, National Research Foundation of Korea, and others. For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.