ESTRO 2022 - Abstract Book

S386

Abstract book

ESTRO 2022

by 2% for each 1 Gy increase in the mean radiation dose delivered to CAR (95% CI of slope, 1.9 to 2.1;p<0.001)(Fig.1). From conditional logistic regression, rate ratio for CD among patients with PCD was similar to those without PCD (RR=1.01, 95% CI, 0.74 to 1.36;p=0.97).

Conclusion This study demonstrates that risk of CD increases with mean dose to CAR, mostly located at the base of the heart, by 2% per Gy. This study could not identify any apparent threshold for CD due to dose to CAR. The percentage increase in the risk of CD per Gy increase in the mean CAR dose was similar for patients with and without PCD. However, for a given dose to CAR, the absolute increase in the risk of CD for patients with PCD will be different due to baseline risk being different. A future study will evaluate the impact of reducing dose to CAR on lung cancer survival in our institution.

OC-0442 Association of sinoatrial node radiation dose with atrial fibrillation and mortality in lung cancer

K.H. Kim 1 , J. Oh 2 , J.S. Chang 1 , H.I. Yoon 1

1 Yonsei Cancer Center, Radiation Oncology, Seoul, Korea Republic of; 2 Severance Cardiovascular Hospital and Cardiovascular Research Institute, Cardiology Division, Seoul, Korea Republic of Purpose or Objective 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 Materials and Methods 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. Results 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. Conclusion 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.

Proffered Papers: Gynaecology

OC-0443 3D-Image-guided brachytherapy plus irradiation in stage-I-III inoperable endometrial cancer.