대한대장항문학회

Purpose : Depressed colorectal cancer is a newly recognized colorectal cancer. It has the<br>characteristics of rapid growth and early invasion of the submucosa. Accordingly, recognition<br>of that lesion is important. However, it is still rarely detected in Korea. This study was<br>designed to evaluate the characteristics of depressed colorectal neoplastic lesions. Methods :<br>We experienced 22 cases of depressed neoplastic lesions from January 1997 to December<br>1998. All of them were detected by performing colonoscopy. Among them, 6 were early<br>colorectal cancers. The twenty-two cases accounted for 1.3% of all neoplastic lesions but<br>advanced colorectal cancers encountered during the same period, and the six accounted for<br>6.6% of all early colorectal cancers during that period. We reviewed and analyzed those 22<br>lesions with respect to their clinicopathologic characteristics, especially size and histology.<br>Results : The most common age group was the 6th decade. The male-to-female ratio was 2.7<br>to 1. The predilection of sites were the descending colon, the transverse colon, and the<br>sigmoid colon in that order. The most common size was 3∼4 mm, 9 lesions (40.9%) and the<br>next was 5∼6 mm, 7 lesions (31.8%). Twenty lesions (90.9%) were 8 mm or smaller in size.<br>The overall malignancy rate was 27.3% (6/22), comprising 9.1% (2/22) for mucosal cancers,<br>and 18.2% (4/22) for submucosal ones. The two lesions which were larger than 10 mm were<br>submucosal cancers. Endoscopic mucosal resection (EMR) was the most common type of<br>treatment, accounting for 59.1%. Two submucosal cancers and one mucosal cancer were<br>operated on without any endoscopic treatment. That one mucosal cancer had initially been<br>suspected of being a submucosal one upon endoscopic examination. There were neither<br>complications nor recurrences during the average 10-month follow-up. Conclusions : The<br>target for detecting and treating depressed colorectal cancer should be lesions below 10 mm<br>in size, and the treatment of choice should be EMR.<br>