Difference between right-sided and left-sided colorectal cancers: from embryology to molecular subtype.

INTRODUCTION: Colorectal cancer is one of the most common malignancies in the world, and it exhibits differences in incidence, pathogenesis, molecular pathways, and outcome depending on the location of the tumor. Differences in the microbiome, clinical characteristics, and chromosomal and molecular characteristics have been reported between the right and left side of the colon. Areas covered: This review focuses on the latest developments in epidemiological and chromosomal and molecular studies, which have enhanced our understanding on the underlying genetic and immunological differences between the right-sided colon and the left-sided colorectum in metastatic colorectal cancer. Expert commentary: The numerous findings regarding differences between right- and left-sided colon cancers should have an impact on colorectal cancer screening and therapy. The location of the colorectal cancer should be considered before group stratification into genetic, clinical, and especially chemotherapy trials. A more tailored approach to colon cancer treatment would be highly desirable if future trials further support the hypothesis of two distinct tumor entities.