| [ Summary ] |
Development and progression of colorectal cancers were studied by examing growth patterns in resected submucosal invasive cancers. These pathological lesions were classified into two types, polypoid growth type (PG) and nonpolypoid growth type (NPG), based on cross sectional views. NPG type cancers tended to show massive submucosal invasion, even when extremely small, compared to PG type cancers. NPG type cancers were found to originate from intramucosal superficial type cancer (IIc, IIc+IIa and IIa gross type) through the study of intramucosal lesions associated with submucosal invasive cancers. Submucosal invasive NPG type cancers tended to change their macroscopic features Is to type2 advanced cancers shape with the progression of submucosal invasion. Most of the advanced cancers smaller than 20mm in diameter consisted of NPG type cancers. In contrast, the ratio of PG type to NPG type cancers, which had invaded deeply into the submucosal layer (sm2, sm3) was equal. However, NPG type cancers (13.1mm) were extremely smaller than PG type cancers (24.1mm in size). In conclusion, the main origin of development for advanced cancers of less than 20mm in diameter was suggested to be from superficial type cancers. |