A fecal metagenomic analysis revealed that mice with colorectal cancer (CRC) treated with 42-day FMD were enriched with Bifidobacterium pseudolongum, which promoted the differentiation of CD8+ T cells into memory cells by generating L-arginine, thereby synergistically demonstrating the anti-tumor effect of oral decisive therapies on colorectal cancer [54]. This evidence concerns the gene CD8A and colorectal cancer.