CEACAM5 and Oral leukoplakia: Zheng et al investigated the serum and salivary CEA levels in precancerous and cancerous lesions, including OLP, leukoplakia, and squamous cell carcinoma, showing an increased level of CEA in serum and saliva in patients with malignancy.17 Also, Li et al,18 investigated the CEA levels in patients with oral SCC.