Lung dose and pulmonary function decline after postoperative radiation therapy for non-small cell lung cancer: a predictive model approach

This study investigated the impact of lung radiation dose on longitudinal pulmonary function decline in patients with non-small cell lung cancer (NSCLC) undergoing postoperative radiation therapy (PORT), with the aim of establishing predictive models for individualized risk estimation. Among 227 patients treated with PORT between 2002 and 2017, 61 patients with spirometry data at three time points—before surgery, before PORT, and at least once after PORT—were included in the analysis. Lung dose parameters, including mean lung dose (MLD) and V5–V50, were calculated, and linear mixed-effects models were used to evaluate their association with changes in forced expiratory volume in one second (FEV1) over time. Higher lung doses, pneumonectomy, and longer time since PORT were significantly associated with greater FEV1 decline, while higher preoperative FEV1 was linked to better preservation of lung function. Postoperative chemotherapy was not significantly associated with pulmonary function decline. The predictive models estimated that each 1 Gy increase in MLD and each month elapsed after PORT corresponded to 0.028 L and 0.003 L reductions in FEV1, respectively. These findings support the development of a predictive model that incorporates preoperative FEV1, surgical extent, lung dose, and time since PORT to estimate potential longitudinal decline in pulmonary function.