The following is the summary of “Cardiac Function Modifies the Impact of Heart Base Dose on Survival: A Voxel-Wise Analysis of Patients With Lung Cancer From the PET-Plan Trial” published in the January 2023 issue of Journal of thoracic oncology by Craddock, et al.
Radiation therapy for non-small cell lung cancer has shown that heart dosage is an independent predictor of overall survival. There have been a number of studies that pinpoint the base of the heart as a place of increased dosage sensitivity and a possible target for cardiac sparing. In this study, we offer the first dosimetric analysis of overall survival in the multicenter, randomized PET-Plan trial (NCT00697333) by including baseline left ventricular ejection fraction (EF) as a metric of cardiac function. The 205 participants in this trial all had incurable stage II or III NSCLC, and they were all given 60 to 72 Gy in 2 Gy portions. Anatomical regions where the higher dosage was significantly related with poorer overall survival were identified using a voxel-wise image-based data mining process.
The relationship between survival and dose to the targeted area recognized prognostic variables, and preexisting heart function was evaluated using univariate and multivariate Cox proportional hazards models. After data cleaning and filtering, 172 patients were left for further study. The origin of the left coronary artery and the area around the atrioventricular node was found to be a highly significant region within the base of the heart at 2 years post-treatment (P<0.005). A number of positron emission tomography-positive lymph nodes (P=0.02, hazard ratio =1.13, 95% CI: 1.02-1.25) and mean dose to cardiac subregion (P=0.02, hazard ratio=1.11 Gy-1, 95% CI: 1.02-1.21) were independently associated with overall survival in multivariable analysis.
Patients with lower EF values showed a greater influence of region dose on survival, as seen by contrast plots, suggesting an interaction between EF and region dose for survival (P=0.04). A substantial correlation between dose to the base of the heart and overall survival was discovered, validating prior image-based data mining research. The effect of heart dose on survival was found to vary depending on the patient’s baseline cardiac health and the dose delivered to the heart, suggesting that underlying cardiac dysfunction amplifies the effect of heart dose.