Characteristics of Colorectal Cancer and Adenoma Observed in Surveillance Colonoscopy After Endoscopic Resection of All Neoplasms

Abstract

Aim: Little is exactly known about the speed of growing and invading of colorectal cancer in early stage and recurrence rate of tumors. We must elucidate this problem, to make the optimal guideline for surveillance colonoscopy after colonic tumor resection. Method and Object: From 1988 to 2003, consecutive colonoscopies were designed to make colon free of cancer and adenoma, (namely clean colon). All cancer and adenoma was entirely resected in each colonoscopy. Tumors found after this clean colon procedure are representative of newly borne tumors in earlier stage. We compared the data of tumors between initial cases and surveillance cases. The initial ones were 5902 cases and mean age was 54.2 and gender ratio was 28%. The surveillance ones were 17178 colonoscopies, average of interval was 413 day and mean age was 58.6 and gender ratio was 25%. The time of observation was 19434 person-year. Results: In the initial data, there were 94 advanced carcinoma, 82 submucosal cancer (including 24 pedanculated and 14 depressed submucosal cancer), 707 intramucosal cancer (including 258 pedanculated and 24 depressed cancer), 606 adenoma with high grade dysplasia (including 152 pedanculated and 28 depressed), 11089 adenoma with low grade dysplasia (including 378 pedanculated and 1152 depressed), 202 villous tumor, 25 serrated adenoma. In surveillance data, there were 3 advanced carcinoma, 7 submucosal cancer (including 0 pedanculated and 5 depressed submucosal cancer), 46 intramucosal cancer (including 4 pedanculated and 15 depressed cancer), 81 adenoma with high grade dysplasia (including 5 pedanculated and 21 depressed), 13328 adenoma with low grade dysplasia (including 25 pedanculated and 2558 depressed), 10 villous tumor, 13 serrated adenoma. In surveillance, advanced cancers, pedanculated tumors and villous tumors were small in number. This means that it takes more than one year for them to develop their own stage. In surveillance data, the rate of sm cancer in depressed cancer became about 5 times higher than that of other type of cancer. This means that depressed cancer invades 5 times faster than other type of cancers. Conclusion: In the surveillance colonoscopy, the most dangerous lesion was depressed cancer, which was estimated to invade 5 times faster than other type of cancer. It is estimated that it takes more than one year to form the pedanculated shape and villous histological pattern.