Author: Ryan Gentzler, Xin He, James Larner, J.T. Morgan, Cam Nguyen, Wendy Stewart, Krishni Wijesooriya, Grant Williams 👨🔬
Affiliation: Department of Physics, University of Virginia, Department of Radiation Oncology, University of Virginia, Division of Hematology & Oncology, Department of Medicine, University of Virginia 🌍
Purpose: Some recent studies have shown Overall Survival (OS) of advanced-stage lung cancer patients treated with chemo-radiation therapy (CRT) is correlated with heart dose [1-5], while in other studies, heart dose was found to not be correlated [6-10]. Results from a recent clinical trial for early-stage lung cancer patients showed radiation-induced immune suppression (RIIS) and OS are correlated with lymph node dose [11]. In this abstract, we investigate the correlation of OS and RIIS with patient and dosimetric characteristics, including dose to immune rich organs, in advanced-stage NSCLC patients.
Methods: Data from 51 advanced-stage NSCLC patients treated with RT-only or concurrent CRT were collected, including dosimetric parameters (integral dose, V5 to V50) for immune-rich organs. Lymph node structures were contoured using eContour atlas [12]. Age, sex, PTV volume, pre-tx ALC, non-chemo vs. concurrent chemo, number of RT fractions, and dosimetric parameters of total lungs-GTV, heart + great vessels (heart+GV), lymph node-GTV (LN-GTV, to exclude draining-LNs), thoracic spine, were analyzed for correlation with fractional drop of post-tx absolute lymphocyte count (ALC) with respect to pre-tx ALC (using Spearman’s correlation for quantitative parameters and point-biserial correlation for categorical parameters), and OS (using Cox proportional hazards model).
Results: Larger fractional ALC drop were found to be statistically significantly correlated with younger age, higher number of fractions, higher LN-GTV dose (V40, V50), heart+GV dose (integral dose, V10, V30, V40, V50), thoracic spine dose (V30, V40, V50), and total lungs-GTV dose (integral dose, V5, V10, V20, V30, V40, V50). Poor OS were found to be statistically significantly correlated with larger PTV, lower pre-tx ALC, LN-GTV dose V5, V10, V20. Non-chemo patients had less severe RIIS, but poorer OS, compared to concurrent CRT patients
Conclusion: Dose to non-draining lymph node possibly play an important role in both severe RIIS and lower OS in advanced-stage NSCLC patients.