Association Between Lung Volume Reduction and Symptomatic Radiation Pneumonitis in Lung Cancer Patients Undergoing...

This study assessed lung volume alterations during radiotherapy (RT) and their predictive value for symptomatic radiation pneumonitis (RP) in lung cancer patients undergoing definitive concurrent chemoradiotherapy (CCRT) MATERIALS AND METHODS: This retrospective study included 49 patients who underwent re-simulation four-dimensional (4D) computed tomography (CT) during RT. Lung volume was measured on the 30% phase of 4D CT at initial and re-simulation scans. Associations between volume changes and symptomatic RP were analyzed using the Mann-Whitney U test. To determine the optimal cut-off value, ROC analysis and the Youden index were utilized. RP was graded based on CTCAE v5.0.

Among the 49 patients, seven (14.3%) developed symptomatic RP. Dosimetric parameters did not differ significantly between patients with and without RP. However, changes in ipsilateral lung volume were significantly associated with symptomatic RP. A volume decrease >130 cm³ or a relative reduction <-7% was predictive of RP (P = .001). The area under the ROC curve for absolute change and relative change of ipsilateral lung volume were 0.905 and 0.883, respectively.

Ipsilateral lung volume reduction during RT may serve as an early predictor of symptomatic RP, independent of traditional dosimetric factors. Monitoring volume changes with re-simulation CT could enhance RP risk assessment and guide adaptive RT planning.