HOXA9 and lung cancer: Although our previous study had demonstrated the high diagnostic sensitivity and specificity of promotor methylation of CDO1, TAC1, HOXA7, HOXA9, and SOX17 in plasma from patients with NSCLC in a Lung Cancer Specialized Program of Research Excellence (SPORE) patient cohort [18, 23], the performance and diagnostic accuracy of these biomarkers still needed validation in another cohort, and might be affected by differences between races, environmental carcinogenic exposure, and smoking status.