Gastric carcinoma. A pathobiological classification.

Gastric carcinomas had various pathological features. Based on patterns of growth and invasiveness, however, they fell into two types; expanding type and infiltrative type. These types were readily recognizable histologically: expanding carcinomas grew en masse and by expansion, resulting in the formation of discrete tumor nodules, whereas in infiltrative carcinoma tumor cells invaded individuality. Both types showed varying degrees of cell maturation, but glands were much more common in expanding carcinoma. The difference in growth pattern was reflected partly by gross appearance of the tumors. These two types of carcinoma appeared to be different in their histogenetic origins. Intestinal metaplasia probably played a role in the development of expanding, but not infiltrative, carcinoma. There were differences also in the sex and age of the patients, survival rate, and epidemiological distribution. Thus, this classification provided a simple basis for evaluation of various aspects of gastric cancer.