CEACAM6 and cancer: Furthermore, there was no statistically significant difference in serum CYFRA 21–1 levels between the LUAD group and the benign nodules group.[35] While, in this study, the AUC for CEACAM6 in differentiating between benign nodules and LUAD was 0.77, with a sensitivity of 71% % at a specificity of 82%, which proved that it can be a promising biomarker for identification of malignant pulmonary nodules at early stage of LUAD.