| [ Summary ] |
To confirm of the basis for the existence of depressed-type colorectal tumors, we analyzed 11,296 adenomas and early colorectal cancers that were detected via magnifying colonoscopy and resected. The lesions were classified as the protruded type (n=5,934), flat type (n=5,255), and depressed type (n=107) according to their developmental morphology and compared clinicopathologically. The incidence of the depressed-type tumors was 1.0 %. The rate of T1 cancer was 21.5 % in the depressed-typed tumors compared with 0.5 % in the protruded-type and 0.4 % in the flat-type tumors (p<0.0001). In the depressed-type tumors, the rates of T1 cancer in type IIc and IIc+IIa, type IIa+IIc, and type Ⅰs+IIc were 3.3 %, 26.6 %, and 38.5 %, respectively. Thus, we reconfirmed the malignant potential of depressed-typed colorectal tumors, as previously reported, and verified the basis for their existence at the time of diagnosis using image-enhanced endoscopy or artificial intelligence. |