Colonoscopic polypectomy is considered effective for preventing colorectal cancer.
The incidence of cancer in patients under colonoscopic surveillance has rarely been investigated.
Dr Douglas Robertson and colleagues determined the incidence of colorectal cancer in patients under colonoscopic surveillance.
The investigators examined the circumstances and risk factors for colorectal cancer and adenoma with high-grade dysplasia.
The investigative team drew patients from 3 adenoma chemoprevention trials.
All patients underwent baseline colonoscopy with removal of at least 1 adenoma and were deemed free of remaining lesions.
The investigators identified patients subsequently diagnosed with invasive cancer or adenoma with high-grade dysplasia.
|84% of the cancers were of early stage and 2 participants died of colorectal cancer|
The team identified the timing, location, and outcome of all cases of cancer and high-grade dysplasia and explored risks associated with their development.
The investigators noted that colorectal cancer was diagnosed in 19 of the 2915 patients over a mean follow-up of 4 years.
The team found that the cancers were located in all regions of the colon, and 10 were at or proximal to the hepatic flexure.
Although 84% of the cancers were of early stage, 2 participants died of colorectal cancer.
The investigators noted that 7 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.
Dr Robertson's team concludes, “Colorectal cancer was diagnosed in a clinically important proportion of patients following complete colonoscopy and polypectomy.”
“More precise and representative estimates of colorectal cancer incidence and death among patients undergoing surveillance examinations are needed.”