For the subgroup ESCC patients with early clinical stage, a significant benefit in OS was observed in patients with low serum level of P. gingivalis IgA but non-significant for IgG than in patients with high level (log-rank test, x2 = 9.141, P = 0.003, Additional file 1: Figure S1B & D), and neither IgG nor IgA was associated with OS of late stage ESCC (Additional file 1: Figure S1C &E). Here, CD79A is linked to esophageal squamous cell carcinoma.