Hereditary Colorectal Cancer.

Around 10% to 16% of colorectal cancer patients have a pathogenic variant in a cancer susceptibility gene. Some of these variants are in cancer genes that are associated with colorectal cancer while others are not. The hereditary colorectal cancer syndromes can be divided into two major categories, the nonpolyposis and the polyposis conditions. The nonpolyposis conditions can be divided into those that lead to colorectal tumors with defective mismatch repair and those that do not. The polyposis conditions are further divided by predominant histology into the adenomatous, hamartomatous, serrated, and mixed polyposis conditions. All of these conditions are described in detail herein.