4516 A clinicopathological study of small advanced colorectal carcinomas.

Abstract

Not only depressed early colorectal cancers but also "small" advanced colorectal cancers (less than 2cm in diameter) have been gradually detected year by year. The latter are thought to be situated between early cancers and "large" advanced cancers and seem to have significant lesions in order to solve a key of "developmental process of colorectal neoplasms". Materials and Methods: From April 1985 to August 1999, 52 small advanced colorectal cancers(less than 2cm in diameter), and 249 submucosal invasive cancers(less than 2cm in diameter), were resected endoscopically and surgically. In terms of the lesions mentioned above, a clinicopathological study was conducted. In this study, all of the lesions were macroscopically classified into three as follows: protruded, flat and depressed types. The depth of submucosal invading carcinomas was divided into three categories: sm1, sm2 and sm3, according to Kudo's classification. Results: Of "small" advanced cancers, 82.7% were depressed type, 16.3% for protruded type and 1.0% for flat type.The degree of cancerous invasion was as follows: depressed type( 42.9% for invasion into the muscularis propria-mp, 57.1% for invasion beyond mp), protruded type( 66.7% for invasion into mp, 33.3% for invasion beyond mp) and flat type (100% for invasion into mp). Average size was as follows: 16.9mm for depressed type, 18.4mm for protruded type and 17.0mm for flat type. On the other hand, of submucosal invasive cancers, 40.3% were depressed type, 54.0% for protruded type and 5.7% for flat type. The rate of degree of cancerous invasion was as follows: depressed type( 40.0% for sm1, 60.0% for sm2,3), protruded type( 57.9% for sm1, 42.1% for sm2,3) and flat type (28.6% for sm1, 71.4% for sm2, 3). Average size was as follows: 10.4mm for depressed type, 13.4mm for protruded type and 15.3mm for flat type. Depressed type of submucosal invasive cancer has a higher rate of massive invasion, in spite of its smaller size, compared with the other types. Moreover, about 80% of "small" advanced cancers are depressed type, which are also invasive. Both of the two cancers mentioned above resemble macroscopically. Conclusion: Most of the small advanced colorectal cancers are thought to be derived of depressed early colorectal cancers because of their tendency toward submucosal invasion and the similarities of morphology.