Age, lung V20 predict radiation pneumonitis
Age ≥60 years and ≥20 percent of normal lung volume receiving a radiation dose of ≥20 Gy (V20) are significant predictors of radiation pneumonitis (RP) in patients treated with intensity-modulated radiotherapy (IMRT) for lung cancer, a Chinese study has shown.
“The study aimed to correlate clinical and dosimetric factors with the development of RP in patients with lung cancer treated with IMRT,” noted researchers from the PLA General Hospital, Beijing, China, at the International Association for the Study of Lung Cancer (IASLC) 19th World Conference on Lung Cancer (WCLC 2018).
The study included 149 patients with lung cancer (squamous cell carcinoma, 30.2 percent; adenocarcinoma, 18.8 percent; small cell lung cancer, 38.2 percent; others, 12.8 percent). Most patients had stage III (65.1 percent) or IV disease (28.2 percent). Potential predictive factors for RP investigated in the study included age, gender, histology, tumour stage, pulmonary function, Karnofsky performance score, radiation dose, surgery history, and chemotherapy use. [Du L, et al, WCLC 2018, abstract P1.17-19]
After a median follow-up of 9 months, 62.7 percent, 38.3 percent, and 6.7 percent of the patients developed grade ≤1, grade ≥2, and grade ≥3 RP, respectively.
In multivariate analysis, age ≥60 years (age ≥60 years vs <60 years, adjusted hazard ratio [aHR], 2.517; 95 percent confidence interval [CI], 1.167 to 5.430; p=0.019) and V20 ≥20 percent (V20 ≥20 to <25 percent vs <20 percent, aHR, 2.971; 95 percent CI, 1.085 to 8.133; p=0.034; V20 ≥25 percent vs <20 percent, aHR, 5.810; 95 percent CI, 1.391 to 24.27; p=0.016) were significant predictors of grade ≥2 RP. Patients with a history of surgery were also more prone to grade ≥2 RP, but the predictive value reached only borderline significance (vs no surgery, aHR, 3.048; 95 percent CI, 0.959 to 9.686; p=0.059). Other potential factors failed to demonstrate statistical significance.