[Genetic anomalies of colorectal cancers].

The prognosis of colorectal cancer has been based essentially on pathological data for many years. The analysis of genetic anomalies has led to fundamental progress and clinical advances. Genetic anomalies are routinely studied. 1--Flowcytometry evaluates the quantity of DNA in the nucleus during the cell cycle. 2--Cytogentics is the study of karyotype anomalies by loss or gain of chromosome material and structural changes. 3--Molecular biology gives a means of recognizing chromosome losses and especially to study oncogenic or antioncogenic mutations. These analyses allow: 1--an evaluation of their value as a prognosis factor and thus their use for indicating adjuvant medical and/or surgical treatments. 2--an understanding of cancerogenic processes. 3--the development of future therapeutic techniques based on a better understanding of the mechanisms involved. 4--familial counselling in high risk families and an examination of responsible or favouring genes in certain familial cancers. Research into familial forms has recently led led to the demonstration of genetic alterations located on chromosomes 1 and 2. These anomalies called RER correspond to alterations found on tumors. Studying these alterations will allow better prediction of high risk subjects in cancer families without polyposis.