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. This evidence concerns the gene TAC1 and lung cancer.