In their study, Zheng J. et al. found that salivary CEA levels in patients with OSCC correlated with clinical staging and lymph node metastases, so salivary CEA can be used as an indicator of OSCC severity and serve as a method for assessing OSCC staging and lymph node invasion. This evidence concerns the gene CEACAM5 and metastatic malignant neoplasm in the lymph nodes.