In addition, certain microbiota have been linked to alteration in the tumor immune micro-environment, e.g., Tumor-derived CCL20 activated by F. nucleatum not only increases CRC metastasis, but also participates in the reprograming of the tumor immune microenvironment via several mechanisms including M2 macrophage polarization (Xu et al., 2021). This evidence concerns the gene CCL20 and colorectal carcinoma.