We used ROC curve analysis to evaluate the sensitivity and specificity of ELF-napsin A and ELF-CEA as biomarkers for distinguishing primary lung adenocarcinoma (resected from 29 nodule sites) from normal tissue and non-adenocarcinoma (resected from 29 contralateral sites in primary lung adenocarcinoma and 12 bilateral sites in non-adenocarcinoma) (Fig. 6). The gene discussed is NAPSA; the disease is lung adenocarcinoma.