Dominant microorganisms within tumors, such as Saccharopolyspora, Pseudoxanthomonas, and Streptomyces, are beneficial to promote the recruitment and activation of CD8 T cells, which can produce plenty of anti-tumor cytokines (such as TNF-α and IFN-γ), thereby enhancing the anti-tumor immune response (29). This evidence concerns the gene CD8A and neoplasm.