Session Item

Radiotherapy-associated cardiac toxicities in patients with small cell lung cancer (SCLC) has largely been unexplored. The purpose of this study was to describe the cardiac adverse events in SCLC and determine predictive dosimetric parameters

Between August 2008 and December 2019, 239 patients with histologically confirmed limited-stage SCLCs treated with definitive chemoradiotherapy were analyzed retrospectively. Dose-volume histograms of cardiac substructures were calculated for each patient. 

At a median follow-up time of 26 months (IQR, 17–47 months), nine patients experienced new-onset atrial fibrillation (AF) and five patients experienced non-AF cardiac events (acute coronary syndrome or heart failure hospitalization). The maximum dose delivered to the sinoatrial node (SAN D_max) exhibited the highest predictive value for AF. The SAN D_max≥53.5 Gy correlated with a significantly higher 1-year cumulative incidence of AF compared with those that received the SAN D_max<53.5 Gy (13.9% vs. 1.0%; P < 0.001). Adjusting for other clinical factors, the SAN D_max≥53.5 Gy correlated with AF (adjusted hazard ratio (aHR) 23.15; 95% CI, 4.91-109.2; P < 0.001) and overall survival (aHR 2.68; 95% CI, 1.53-4.71; P < 0.001). The one-year cumulative incidence of non-AF cardiac events was similar between SAN D_max≥53.5 Gy and SAN D_max<53.5.

Our results generated a strong hypothesis that high doses irradiated to the SAN may facilitate the development of AF and increase mortality, supporting the need to consider the radiation dose exposure to the SAN during radiotherapy planning and close follow-up for the early detection of AF in patients receiving thoracic irradiation.