The following studies were undertaken using specimens of submucosal invasive colorectal cancer surgically or endoscopically resected from 104 patients: 1) measurement of the depth of submucosal invasion; 2-a) histological reevaluation of colon sm cancer by scoring of the degree of histological differentiation using a modified Gleason's grading system proposed for prostatic cancer; and 2-b) immunohistological evaluation of E-cadherin, a cell adhesion factor. Lymphatic node metastasis occurred in no case with the depth of submucosal invasion of less than 1,000 microns. In the histological reevaluation, high incidence of lymphatic metastasis was noted in the high-score group, while lymphatic node metastasis was not seen in any patients in the low-score group. Immunohistological evaluation of E-cadherin showed that the destructive pattern is correlated with lymphatic metastasis, suggesting that weakening of the cell adhesive factor was related to a decline in the degree of differentiation of the tumor. Findings obtained in the present study suggest that endoscopic therapy is indicated for colon cancer measuring less than 1,000 microns and that its indication can be expanded to colorectal cancer with the depth of submucosal invasion of more than 1,000 microns by adding histological reevaluation.