It has been reported that the combined use of N‐α‐acetyltransferase 10 protein (Naa10p) and carcinoembryonic antigen (CEA) as tumor markers for oral squamous cell carcinoma (OSCC) in saliva were more sensitive than that in serum18; MiR‐21 in saliva was increased in colorectal cancer patients with a sensitivity of 97% and a specificity of 91%.19 Importantly, saliva can also be used for cfDNA (scfDNA) detection and analysis. The gene discussed is CEACAM5; the disease is oral cavity squamous cell carcinoma.