The association of chest computed tomography-defined visual emphysema and prognosis in patients with nonsmall cell lung cancer

Background Although computed tomography (CT)-defined emphysema is considered a predictor of lung cancer risk, it is not fully clear whether CT-defined emphysema is associated with the prognosis of lung cancer. We aimed to assess the clinical impact of CT-defined emphysema on the survival of lung cancer. Methods In the prospective cohort study of nonsmall cell lung cancer (NSCLC), the correlation between CT-defined emphysema and clinical variables was analysed. A multivariable Cox regression model was built to assess the association between CT-defined emphysema and overall survival (OS) for up to 8.8 years. The differences in survival analyses were derived by Kaplan-Meier analysis and log-rank testing. Low attenuation area (LAA%) was defined as the per cent of voxels below -950 HU. Results 854 patients were included and CT-defined emphysema was present in 300 (35.1%) at diagnosis. Epidermal growth factor receptor (EGFR) wild-type (OR 1.998; p<0.001) and anaplastic lymphoma kinase (ALK) wild-type (OR 2.277; p=0.004) were associated with CT-defined emphysema. CT-defined emphysema remained a significant predictor of prognosis adjusting for age, sex, smoking history, tumour histology and Eastern Cooperative Oncology Group Performance Status (ECOG PS), whether in I-IIIA stage (adjusted hazard ratio (HR) 1.745; p=0.017) or in IIIB-IV stage (adjusted HR 1.291; p=0.022). Stratified analyses showed that OS rate among the driver oncogene groups with different CT-defined emphysema status differed significantly (log-rank p<0.001). Furthermore, patients with centrilobular emphysema (CLE) with LAA% >17% displayed poorer survival than those with LAA% <= 17% (median 432 versus 670 days; HR 1.564; p=0.020). Conclusions CT-defined emphysema, especially CLE with LAA%>17%, is an independent predictor of NSCLC prognosis. Moreover, prospective studies are needed to further explore this association.