Interestingly, a recent study indicated that the infiltration of CD8 + T cells in the tumor was significantly positively correlated with the abundance of Faecalibacterium, Ruminococcaceae, and Clostridiales and negatively correlated with Bacteroidales(though not significant) [45], revealing intestinal flora may influence T cells infiltrating in tumors. This evidence concerns the gene CD8A and neoplasm.