Our study reveals that s_Bacteroides_finegoldii from p_Bacteroidetes and o_Pasteurellales together with f_Pasteurellaceae from p_Proteobacteria exert inhibitory and promotional effects on PC, respectively, through immune cell phenotypes “CD4 on naïve CD4+ T cell” and “SSC-A on HLA DR+ Natural Killer.” The immune phenotype “CD4 on naïve CD4+ T cell” belongs to the Maturation stages of T cell panel, indicating that s_Bacteroides_finegoldii may affect the maturation process of the aforementioned anti-tumor T cells, thereby inhibiting tumor development. Here, CD4 is linked to neoplasm.