In ESCC patients with negative lymph node metastasis, those with high levels of P. gingivalis IgG or IgA had worse OS than patients with low IgG or IgA serum level (log-rank test, x2 = 6.097/6.097, P = 0.014/0.011, Additional file 2: Figure S2B & D), whereas no significant differences were observed between P. gingivalis IgG or IgA and OS in positive lymph node metastasis (Additional file 2: Figure S2C & E). The gene discussed is CD79A; the disease is metastatic malignant neoplasm in the lymph nodes.