Genetic alterations in human gastric cancer.

Most types of human tumors display a consistent set of genetic alterations that are thought to play a role in tumor development and progression. In the case of gastric carcinomas, consistent genetic changes have been difficult to identify because (1) the tumor DNA samples are often heavily contaminated with DNA from normal stromal cells and (2) the tumors are heterogeneous in origin. However, with the recent application of more refined molecular genetic techniques, it has become clear that gastric carcinomas display some of the same genetic alterations observed in other common carcinomas. These changes include point mutation of the ras oncogene and the p53 tumor suppressor gene, gene amplification, and chromosomal loss of heterozygosity.