[Clinical significance of HNPCC, surgical aspects of early recognition].

A hereditary background may be demonstrated in approximately 15-20% of colorectal carcinomas. Familial adenomatous polyposis syndrome (FAP) constitutes about 1% of this patient population whereas hereditary non-polyposis colorectal carcinoma (HNPCC) makes up a further 3-6% of colorectal malignancies. The clinical features of HNPCC are dominant right colon localization, early age of onset, high prevalence of synchronous and metachronous tumors. Germline mutations of the so-called mismatch repair genes can be demonstrated in the genetic background of HNPCC. Screening and careful follow-up of these families are essential since the lifetime occurrence of colorectal carcinomas and HNPCC associated tumors has an 80-85% prevalence. The recognition of the affected families may be accomplished by taking a thorough family history, spanning several generations based on the Amsterdam and Bethesda Criteria, immunohistological investigations of the removed specimens and finally the exact identification of the pathologic MMR gene mutations. Radical surgical intervention is advised in cases of proven mutation carriers who are suffering from CRC. The index persons and their family members must be under regular control for their lifetime, with one-to-two year intervals to prevent fatal disease. The initiation of a national HNPCC register would further decrease the mortality and morbidity of the disease.