Gastroenterology

Gastroenterology

Volume 129, Issue 1, July 2005, Pages 34-41
Gastroenterology

Clinical-alimentary tract
Colorectal Cancer in Patients Under Close Colonoscopic Surveillance

https://doi.org/10.1053/j.gastro.2005.05.012Get rights and content

Background & Aims: Colonoscopic polypectomy is considered effective for preventing colorectal cancer (CRC), but the incidence of cancer in patients under colonoscopic surveillance has rarely been investigated. We determined the incidence of CRC in patients under colonoscopic surveillance and examined the circumstances and risk factors for CRC and adenoma with high-grade dysplasia. Methods: Patients were drawn from 3 adenoma chemoprevention trials. All underwent baseline colonoscopy with removal of at least one adenoma and were deemed free of remaining lesions. We identified patients subsequently diagnosed with invasive cancer or adenoma with high-grade dysplasia. The timing, location, and outcome of all cases of cancer and high-grade dysplasia identified are described and risks associated with their development explored. Results: CRC was diagnosed in 19 of the 2915 patients over a mean follow-up of 3.7 years (incidence, 1.74 cancers/1000 person-years). The cancers were located in all regions of the colon; 10 were at or proximal to the hepatic flexure. Although most of the cancers (84%) were of early stage, 2 participants died of CRC. Seven patients were diagnosed with adenoma with high-grade dysplasia during follow-up. Older patients and those with a history of more adenomas were at higher risk of being diagnosed with invasive cancer or adenoma with high-grade dysplasia. Conclusions: CRC is diagnosed in a clinically important proportion of patients following complete colonoscopy and polypectomy. More precise and representative estimates of CRC incidence and death among patients undergoing surveillance examinations are needed.

Section snippets

Materials and Methods

We have previously reported the essential features of the design and principal findings of the 3 multicenter randomized trials that form the basis for the current analyses.9, 10, 11 Institutional review board approval to perform the trials and collect the information that is reported herein was obtained from all participating centers in each study. Briefly, patients qualified for study by having at least one histologically documented large bowel adenoma of any size removed shortly before study

Results

A total of 2915 patients were randomized in the 3 trials. The characteristics of the participants differed only moderately among studies, and overall 71% were men, 85% were white, and the average age was 59.7 years (Table 1). Colonoscopic follow-up was essentially complete; 97% (n = 2836) of subjects had at least one examination after the qualifying colonoscopy, and in 91% (n = 2664) follow-up ended with a year-3 (third trial) or year-4 colonoscopy (trials 1 and 2) as per protocol. Most of the

Discussion

In our trials, we followed up 2915 patients with adenomas using surveillance protocols that called for complete colonoscopic examination; 26 of these patients were diagnosed with invasive colorectal cancer or high-grade dysplasia. Of the 19 cancers identified, 8 were stage II or greater; 2 of these cancers ultimately caused the death of the patients. Fifteen (79%) of the cancers were found during a surveillance examination and were apparently asymptomatic. Older age and greater number of

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    Supported by a development award from the Foundation for Digestive Health and Nutrition. The parent studies were supported by grants CA 23108, CA46927, and CA 59005 from the National Institutes of Health.

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