Besides screening for cancer and diagnosing other conditions of the intestines, colonoscopy can also be useful in predicting the development of tumours. Colonoscopy is the endoscopic examination of the large colon and the distal part of the small bowel with fibre optic camera on a flexible tube passed through the anus. Usually, it is recommended as a screening test for colon cancer. However, outcomes of colorectal cancer screening with colonoscopy are uncertain. To assess the use of colonoscopy in detecting advanced tumours, researchers at the Department of Veterans Affairs Medical Center, Portland, Oregon examined the occurrence of advanced colon tumours in patients within 5.5 years of screening colonoscopy. A total of 3,121 subjects between the ages of 50 and 75 years underwent screening colonoscopy between 1994 and 1997 in the Veterans Affairs Cooperative Study. The current analysis focused on 1,171 subjects with growths on the initial colonoscopy and 501 subjects without growths. The subjects were evaluated with repeat colonoscopy over 5 years. The results showed that there is a strong association between results of baseline screening colonoscopy and rate of serious incident lesions during 5.5 years of surveillance. At follow-up, 7.4 percent of patients with growths on the initial test were found to have advanced tumours compared with just 2.4 percent of those without growths. Further analysis showed that the type and number of growths determined the likelihood of finding an advanced tumour on follow-up. Thus, screening colonoscopy can be useful in dividing patients into various risk groups that require more or less frequent follow-up examinations.
Gastroenterology,
November 2007