Fig. 2

Sidedness-associated differences in immune and bacterial abundance within the tumor microenvironment. While LCRC is associated with disease characterized by polypoid adenocarcinomas and chromosomal instability, RCRC is conversely associated with serrated tumor morphology and MSI. On account of the MSI phenotype, immune infiltration is often reported as higher in RCRC, as is the immune and stromal conjugate ESTIMATE score, while tumor purity is accordingly greater in left-sided disease. Even so, certain subsets of immune cells, including natural killer (NK) cells and memory B cells, have been reported as more abundant in LCRC. Meanwhile, the predominant microbiota of RCRC and LCRC tumors have been presented as distinct, with the often RCRC-associated Fusobacterium reported to also dominate the LCRC flora, in addition to the description of various other bacteria as differentially abundant between sides. Data were retrieved from and based on references [34, 55, 59, 67, 97, 117, 124, 127, 129, 130, 137]