Early gastric cancer viewed from its growth patterns

In investigations of the natural history of gastric malignancy, the following conclusions were drawn. There are at least two types of gastric cancers--a rapidly growing penetrating type cancer (Pen) and a slowly growing superficial type (Super). The Super-type cancers are predominately depressed lesions and are associated with favorable prognosis. A subtype of Pen-type cancer, Pen A, is characterized by an elevated lesion and by differentiated carcinoma; its submucosal cancer has a less favorable prognosis than a Pen cancer. The Pen A-type cancer ideally should be treated at the intramucosal stage. A Pen A-type cancer can be differentiated by cytophotometric DNA analysis. It seems that the Super-type early cancer progresses to the funnel-shaped, non-Borrmann advanced type of cancer of a lesser incidence, and the Pen type leads to the most advanced cancer of Borrmann type. Low ploidy DNA patterns are seen in Super- and Pen B-type cancers, while Pen A-type cancer is featured by the high ploidy pattern. A slowly growing Super-type cancer is more likely to be detected because it remains at the early stage for a longer period. Conversely, the rapidly growing Pen-type cancer is less likely to be detected until the cancer has reached an advanced stage. Ulcer symptoms accompanied by the Super type seem to create a detection bias, and the chance of cancer detection is increased. A rough estimation of the occurrence rate of slowly and rapidly growing cancers is about 1:2. The frequent occurrence of slowly growing cancer seems to be characteristic of a gastric cancer, as such is not likely the case with malignant tumors seen elsewhere in the GI tract. We have to direct considerable efforts to studies of rapidly growing gastric cancer; the early detection of Pen-type cancers will be a top priority study in this field. The focus of inspection should be directed to differentiation of "type-oriented early cancer." Nearly 20 years ago we first proposed the concept of the Pen type of early gastric cancer. At that time relatively few investigators seemed to accept our view. However, understanding has gradually increased and infiltrated among Japanese researchers. The Japanese experience with gastric cancer has been thought to be singular because of the high rate of detection of early gastric cancer in these two decades.(ABSTRACT TRUNCATED AT 400 WORDS)