Abstract
In order to study the mechanism of the origin and growth of colorectal cancer, the histopathology of the adenomatous component of early colorectal cancer was studied and correlated with the shape, size and depth of tumor invasion. Among patients with early colorectal cancer, 84.5% of the tumors were associated with an adenomatous component. Most of the early colorectal cancer patients (74.4%) had the protruded type of tumor (Ip, Isp, Is) . Among patients with submucosal invasive cancer (sm cancer), 52.2% has the protruded type associated with an adenomatous component. Of these patients, 61. 9% had cancer that is categorized as“sm cancer with greater depth”according to the Japanese Classification of Colorectal Carcinoma (sm II cancer) . Among patients with early protruded type of colorectal cancer with an adenomatous component, 81.4% has tumor a size greater than 20 mm and 66% had sm II cancer. Among the patients with sm II cancer, 60.9% had what is considered to be “adenomatous type”cancer. Among patients with sm II cancer, 8.6% had de novo type superficial cancer with a size less than 10 mm. These results suggest that a significant number of colorectal cancers are derived from adenoma and invade the submucosal tissues even at an early stage with a tumor size of less than 20 mm.
