This study is the first to report on the diagnostic value of P. gingivalis IgG in OSCC, and the diagnostic performance of a single IgG for OSCC in the present study was superior to that of IgG or IgA for ESCC and achieved a sensitivity of 53.2% and a specificity of 84.4%. The gene discussed is CD79A; the disease is esophageal squamous cell carcinoma.