The term Hereditary Non-Polyposis
Colorectal Cancer (HNPCC) is a poor descriptor of the syndrome described by Lynch. Over the last decade, the term has been applied to heterogeneous groups of families meeting limited clinical criteria, for example the Amsterdam criteria. It is now apparent that not all Amsterdam criteria-positive families have the
Lynch syndrome. The term HNPCC has also been applied to clinical scenarios in which
CRCs with
DNA microsatellite instability are diagnosed but in which there is no vertical transmission of an altered DNA mismatch repair (MMR) gene. A term that has multiple, mutually incompatible meanings is highly problematic, particularly when it may influence the management of an individual family. The
Lynch syndrome is best understood as a hereditary predisposition to
malignancy that is explained by a germline mutation in
a DNA MMR gene. The diagnosis does not depend in an absolute sense on any particular family pedigree structure or age of onset of
malignancy. Families with a strong family history of
colorectal cancer that do not have
Lynch syndrome have been grouped as 'Familial
Colorectal Cancer Type-X'. The first step in characterizing these
cancer families is to distinguish them from
Lynch syndrome. The term HNPCC no longer serves any useful purpose and should be phased out.