Just when you thought there was nothing else to possibly glean from RTOG 0617, this study combined trial data with two large real world cohorts to explore the effect of radiation dose to the thymus on patient outcomes. They used a deep learning model to estimate thymic function based on radiographic characteristics, and they estimated thymic dose for 1107 patients treated with chemoradiation +/- adjuvant immunotherapy for locally advanced NSCLC. They found that incremental increase in mean thymic dose was associated with an increasing risk of distant metastasis. Now, obviously there is serious confounding to account for as patients with more advanced nodal disease would be more likely to get higher dose to the upper mediastinum. However, they also found the detriment was mainly seen in those who had radiographic features of good thymic function before RT. Those with poor thymic function had no detriment. Furthermore, they observed dose-dependent decreases in thymic function and lymphocyte counts after RT. Though the volume receiving a range of dose between 20-50 Gy was important in thymic function, they identified mean dose <35 Gy as a good threshold to shoot for in optimization. | Prudente, Ann Oncol 2026
