Clinical and Dosimetric Factors Predicting Grade ≥2 Radiation Pneumonitis after Postoperative Radiotherapy for Patients with Non-Small Cell Lung Carcinoma

Publication date: Available online 12 April 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Keeratikarn Boonyawan, Daniel R. Gomez, Ritsuko Komaki, Yujin Xu, Chonnipa Nantavithya, Pamela K. Allen, Radhe Mohan, Zhongxing Liao
BackgroundSeveral factors have been linked with the risk of developing radiation pneumonitis (RP) after definitive concurrent chemoradiation (CCRT) for non-small cell lung cancer (NSCLC), but no such factors have been identified for patients who undergo postoperative radiation therapy (PORT) for NSCLC. We hypothesized that the dose-volume tolerance levels for such patients would be lower than those used to predict RP risk after definitive CCRT.MethodsWe retrospectively reviewed radiotherapy, radiographic, and clinical data from 199 patients who had received PORT, with or without chemotherapy, for NSCLC. Potential associations between dosimetric and clinical factors and RP were evaluated in univariate and multivariate Cox regression hazard models and competing risk analysis. Kaplan-Meier analysis was used to estimate overall survival and the cumulative incidence of RP, and receiver operating characteristic (ROC) analysis to identify cutpoints for variables found to influence RP risk. The endpoint was grade ≥2 RP (symptomatic, requiring steroids or limiting instrumental activities of daily living).ResultsThirty-seven patients (19%) developed grade ≥2 RP. Patient-related factors, type of surgery or chemotherapy, and radiotherapy-related factors were not associated with grade ≥2 RP; only lung V10>30% and lung V20>20% predicted grade ≥2 RP. Risk groupings were as follows: high-risk, V10>30% and V20>20% (24 of 72 patients, 33%); intermediate-risk, V10>30% and V20≤20% or V10≤30% and V20>20% (6 of 26 patients, 23%); and low-risk, V10≤30% and V20≤20% (6 of 101 patients, 6%) (P<0.0001). In a subgroup analysis of patients who had had lobectomy, corresponding incidences of RP were: high-risk, 20 of 59 (34%); intermediate-risk, 5 of 22 (23%); and low-risk, 6 of 70 (9%) (P=0.001).ConclusionsThe lung dose-volume variables V10 and V20 predicted risk of grade ≥2 RP among patients who underwent PORT for NSCLC.

Teaser

Because no standard dose-volume criteria have been established for predicting radiation pneumonitis after postoperative radiotherapy for patients with non-small cell lung cancer, we retrospectively analyzed clinical and dosimetric factors from 199 such patients and identified V10 >30% and V20 >20% as cutoff points for that risk.


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