(ChemotherapyAdvisor) – Colonoscopies are associated with reduced risk of death from colorectal cancer, according to results of a large, US population-based case-control study published in the Journal of Clinical Oncology online June 11.

This association was found to be “considerably and consistently stronger” for distal vs. proximal colorectal cancer and overall was “strongest if colonoscopy was performed by a gastroenterologist,” the investigators stated.

Using Surveillance Epidemiology and End Results Medicare data, 9,458 patients 70 to 89 years of age diagnosed with colorectal cancer from January 1998 through December 2002 who died as a result of their disease by 2007 were identified. A total of 3,963 cases (41.9%) were proximal, 4,685 distal (49.5%), and 810 unknown site (8.6%). Also selected were 27,641 controls.

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From January 1991 through six months before a diagnosis of colorectal cancer, colonoscopy was performed in 11.3% of cases and 23.7% of controls. Compared with controls, cases were less likely to have undergone colonoscopy (OR 0.40), they found, with the association being stronger for distal (OR 0.24) than proximal (OR 0.58) colorectal cancer.

“The strength of the association varied with endoscopist specialty,” they reported, with colonoscopy performed by a gastroenterologist significantly more protective for colorectal cancer death than when performed by a surgeon or primary care provider (OR 0.71).