[Hereditary nonpolyposis colorectal cancer. Lynch syndrome]

Hereditary non-polyposis colorectal cancer represent 5% of the colorectal cancer population. It's characterized by an autosomal dominant inheritance; there are two variants: Lynch syndrome I is characterized by predisposition to early onset colorectal cancer, with predominance for proximal location to the splenic flexure and synchronous and/or metachronous colorectal cancers. Lynch syndrome II shares the same features, but shows association with extracolonic cancers, particularly carcinomas of endometrium, ovary and stomach. However, this syndrome is not easily recognized, due to the lack of phenotypical expression as familiar adenomatous polyposis.

The purpose of this report is to review the natural history, diagnosis, treatment, surveillance of the probands and their families, and to update recent research on the genotypic risk biomarkers located in chromosomes 2, 3 and 7.

We analyzed the available literature to discuss the clinical characteristics, pathology, genetics, management, and surveillance of hereditary non-polyposis colorectal cancer.

The diagnosis of hereditary non-polyposis colorectal carcinoma is not a rare event. It requires the demonstration of vertical transmission, therefore, the past history of colorectal cancer in the proband and his family should be carefully taken; including the anatomic site, histology and age at diagnosis.