A pathological study on colorectal cancer. From de novo carcinoma to advanced carcinoma.

The development and progression of colorectal cancer were studied by examining the mode of proliferation of cancer and adenoma in 806 cases (857 lesions) of colorectal cancers and 12 cases of familial polyposis coli. Colorectal cancer was classified into two groups: those accompanied by intramucosal growth or with polypoid growth and those without polypoid growth. Early cancer in the group without polypoid growth was considered to originate from de novo carcinoma of about 5 mm, showing vascular invasion when reaching the size of about 10 mm and then exhibiting massive submucosal invasion. Their cut-surface closely simulated cancer of ulcerative type without polypoid growth which occupied the greater portion of advanced cancer of the large bowel. In other words, ulcerative type cancer without polypoid growth is considered to arise from de novo carcinoma and this type occupies 70-90% of all colorectal cancers. Since the lesions originating from de novo carcinoma develops from an extremely small intramucosal carcinoma and then leads to a massive submucosal growth, immediate partial resection is recommended.