A route of colorectal cancer development other than the adenoma-carcinoma sequence has recently become an issue due to the discovery of depressed-type early colorectal cancers. Moreover, the fact that some polyp-like cancers actually originate from depressed-type lesions has become obvious. Despite the protruding shapes of depressed-type early colorectal cancers, they probably have biological characteristics, which are different from those of the usual polyp lesions. We undertook this study to evaluate the clinical significance of depressed-type colorectal neoplasms. The authors recently experienced 87 cases of depressed-type colorectal neoplasms. Using Kudo's classification, we classified these 87 cases into three types based on their growth patterns, type IIc, type IIa + IIc, and type Is + IIc, and then analyzed these types on the basis of size, type, and submucosal invasion rate. The submucosal invasion rate of cancers of type IIa + IIc was significantly higher than that of type IIc ( p
展开▼
