The gastric precancerous cascade.

Invasive gastric carcinoma is preceded by a cascade of precancerous lesions. The first recognized histologic change is active chronic inflammation, which may persist as such: non-atrophic chronic gastritis (no gland loss), or advance to multifocal atrophic gastritis (MAG), the first real step in the precancerous cascade. The following steps are: intestinal metaplasia (first "complete" and then "incomplete"); dysplasia, first low grade and then high grade (equivalent to "carcinoma in situ"). The following step is invasive carcinoma, which is thought to be associated with degradation of the intercellular matrix.