A Retrospective Study of Risk Factors for Radiation Pneumonitis of Definitive Chemoradiotherapy for the Treatment of Locally Advanced Lung Cancer By Emphysema Quantification

Abstract

ABSTRACT Aim: Radiation pneumonitis (RP) is one of the most crucial adverse events of definitive chemoradiotherapy for the treatment of locally advanced lung cancer. Although chronic obstructive pulmonary disease (COPD) is considered as one of the risk factors of RP, the relationship between RP and pulmonary emphysema (PE) that is a subtype of COPD is not clear. We examined the clinical backgrounds of patients experiencing RP due to concurrent chemodadiotherapy for the treatment of locally advanced lung cancer and evaluated risk factors. Methods: We retrospectively examined patients with locally advanced lung cancer who underwent definitive chemoradiotherapy between Janary 2010 and December 2012. For quantitative assessments of PE, percentage of low attenuation volumes (%LAV) and mean density (MD) were computationally calculated by using AZE Virtual place Fujin (Tokyo). Common Terminology Criteria for Adverse Events (CTCAE) v.4.0 was used to evaluate RP. We evaluated the relationship between clinical backgrounds, the degree of emphysema (%LAV, MD), radiation dose (the percentage of pulmonary volume irradiated to >20Gy (V20), mean lung dose (MLD)) and RP. Results: 33 patients were analyzed, of which 19 (58%) had symptomatic RP (>= Grade2) and 14 (42%) had asymptomatic RP (=Grade1). Age, sex, pathology and stage in patients were similar between both groups. There is no significant difference in forced expiratory volume in 1 second (FEV1) between the symptomatic group and the asymptomatic group (2.23 + -0.60L vs 2.35 + -0.50L, P = 0.296). The symtomatic group had significantly more severe PE (LAV% 10.9 + -8.7% MD -880 ± 21HU) than the asymptomatic group (LAV% 4.4 + -4.0% (P = 0.025), MD -856 + -24 HU (P = 0.002)), respectively. Radiation dose was significantly higher in the symptomatic group (V20 24.6 + -5.1%, MLD 12.9 + -3.4Gy) than the asymptomatic group ((V20 19.9 + -3.3% (P = 0.005), MLD 9.1 + -3.2Gy (P = 0.002)). Conclusions: Severity of emphysma appears to be a factor that can be used to predict RP after concurrent chemoradiotherapy for lung cancer. Disclosure: All authors have declared no conflicts of interest.