Genetic Aspects of Gut Cancer

Abstract

The contribution of genetic predisposition to the origin of cancer may be much greater than has been supposed. In particular there has been gradually increasing evidence that for nearly all cancers there is at least one form which is inherited in a simple mendelian manner. In the past only certain rare tumours were known to be determined by simple genetic mechanisms and the genetic predisposition to most common cancers was considered to be vaguely polygenic, probably with genes at a large number of loci each able to make a small contribution by susceptibility to one or more environmental agents. This quantitative basis of genetic susceptibility may still underlie many sporadic cases of cancer but there is growing evidence in some of these polygenic systems that there can be one or more major genes which, when present, are able to cause cancer with only minimal environmental stimulus. Such major genes can be responsible for occasional familial aggregations of a cancer suggestive of mendelian type of inheritance. It is hoped that intensive study of this type of family will identify such major genes and their biochemical or immunological effects and thus provide insights into the nature of the carcinogenic process.