Korean experience of superficial depressed‐type early colorectal cancer

Abstract

Background: Unlike the adenoma–carcinoma sequence theory, the de novo carcinoma theory has been highlighted recently because of the emergence of superficial depressed‐type early colorectal cancers. In addition, some flat‐elevated or sessile‐type early colorectal cancers have been identified as originating from superficial depressed‐type early colorectal cancers. Thus, studies of superficial depressed‐type early colorectal cancers may provide an opportunity to clarify the morphogenesis of colorectal cancers in the foreseeable future.Methods: The authors studied 231 cases of early colorectal cancer from 1997 to 2000. Among them, 17 cases (7.4%) were superficial depressed‐type. According to Kudo's classification, the 17 lesions were classified as three types based on their growth patterns: IIc, IIa + IIc, and Is + IIc. They were also classified as sm‐s (sm1) and sm‐m (sm2–3) cancers based on the depth of submucosal invasion according to Kudo's classification. They were analyzed with emphasis on size, depth of submucosal invasion and treatment.Results: Type IIc lesions were 11 mm in diameter on average; types IIa + IIc and Is + IIc had diameters of 15 mm and 11 mm on average, respectively. Sm‐m cancers' diameters were all larger than 10 mm. Fifty‐seven percent (57%) of type IIc cancers were submucosally invasive, while 90% of type IIa + IIc and type Is + IIc cancers together were submucosally invasive. The overall surgical resection rate was 41.2%, and surgical resection was performed in 80% of the sm‐m cases.Conclusion: Recognition of superficial depressed‐type early colorectal cancers, especially type IIa + IIc and type Is + IIc cancers, is important because their biological behavior will most likely be different from that of the usual protruding early cancers. Accordingly, the treatment modality should be selected prudentially, and early detection is imperative in order for their sizes to be less than 10 mm.