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ASTRO 2022: Is Radiotherapy Safe for Cardiac Structures in Patients With Locally Advanced NSCLC?

By: Joshua Swore, PhD
Posted: Tuesday, November 8, 2022

Findings presented at the 2022 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 203) suggest that the radiation dose to cardiac structures may impact overall survival of patients with locally advanced non–small cell lung cancer (NSCLC). “Specifically, we found superior vena cava and whole-heart dosimetric parameters consistently associated with overall survival. We further recommend reducing whole heart and superior vena cava dose in treatment of [NSCLC],” said Miguel Garrett Fernandes, MS, a PhD student at Radboud University Medical Center, Nijmegen, the Netherlands, and colleagues.

The retrospective data set used in the study consisted of 953 patients with stage III NSCLC. All patients had been treated with 66 Gy in 24 to 33 fractions via intensity-modulated radiation or volumetric radiation arc therapy and had received concurrent, sequential, or no chemotherapy. The authors used a deep learning model to collect heart, chamber, and great vessel contours.

Next, a Cox regression model was used to assess survival and identify correlated parameters. The regression model was developed by using fivefold cross-validation with a 20% training set. The authors explained that a fixed number of noncorrelated parameters were randomly selected, and selection was repeated 1,000 times. The parameters with the highest c-index were kept. By repeating the selection method, the authors found the best models included four parameters with limited overfitting.

The investigators reported a median overall survival of 25 months (95% confidence interval [CI] = 22–27 months), with a median follow-up of 42 months (95% CI = 40–46 months). The Cox regression models achieved an average c-index of 60.95 during testing. All five cardiovascular dosimetric parameters chosen for the models had statistically significant hazard ratios. Furthermore, two model splits associated dosimetric parameters with the superior vena cava (V60 and D80) and three associated them with the whole heart (D35, D25, V5).

Disclosure: Mr. Fernandes reported no conflicts of interest.


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