| [ Summary ] |
In the past, the developmental processes related to colorectal cancer were thought to arise from adenomas, and that de novo cancers which arise from normal colon mucosa were very rare. However, it was determined through examination of polypoid type of cancers, which were defined as carcinomas, that atypical neoplastic glands were invading the submucosal layer. After the publication of findings on superficial depressed type of early cancers by Prof. Kudo, superficial type many cancers have been detected in Japan. de novo cancers are therefore thought to be relatively common. Because of improved detection of superficial type cancers, the histopathological definition of carcinomas in situ has gradually changed. Today, endoscopists find the whole types of early colorectal cancers. In analyzing those cancers, pathologists need to standardize the criteria for carcinoma in situ as well as histopathological fi gures, and then will discuss the existence of de novo cancers. |