HEREDITY, MOLECULAR-GENETICS AND COLORECTAL-CANCER - A REVIEW

It is estimated that the hereditary polyposis and non-polyposis colore ctal cancer (CRC) syndromes, which have an autosomal dominant pattern of inheritance, represent less than 10% of the total CRC burden. Thus, more than 90% of all cases of CRC have previously been considered to arise 'sporadically', with no identifiable genetic link. However, rece nt clinical evidence now suggests that a significant proportion of CRC seen in the general population may involve an inherited genetic susce ptibility. Therefore, constructing an accurate family tree on all pati ents with a family history of CRC is an essential part of identifying families with an increased risk for CRC who could then be offered scre ening. Also, molecular genetic study of colorectal adenomas and carcin omas has led to a proposed genetic model of colorectal tumorigenesis w hich involves interactions between oncogenes and tumour suppressor gen es. This information has important potential implications for screenin g, determining prognosis and for providing multiple targets for alteri ng the sequence of malignant transformation.