Colonoscopy is more effective than flexible sigmoidoscopy for the detection of colorectal cancer in elderly patients, according to researchers at the Mayo Clinic in Florida.
Medicare records of more than 25,500 patients 67 years or older in whom colorectal cancer was detected 6 to 36 months after lower endoscopy screenings revealed that left-sided cancer was 4 times more likely to be missed in patients who underwent sigmoidoscopy.
Yize Richard Wang, MD, PhD, a GI fellow at the Mayo Clinic and the study's lead author, admits he couldn't pinpoint exactly why sigmoidoscopies failed to identify cancer as reliably as colonoscopies did, but suggests the lower detection rates could be related to differences in bowel preparation and patient sedation as well as limited views of the colon obtained during sigmoidoscopies.
Although Dr. Wang says colonoscopy is a more expensive option, difficult for patients to prep for and results in post-procedure discomfort, he calls the popular screening method the "gold standard" for detecting or preventing colorectal cancer and advises older patients to opt for it over sigmoidoscopy.
That doesn't mean sigmoidoscopy is headed toward obsolescence. Thomas Semrad, MD, assistant professor of internal medicine at the University of California Davis Medical Center in Sacramento, says the test is easier to perform and less burdensome for patients, making it an appropriate choice in certain circumstances, notably for individuals who would avoid colorectal screening altogether over fears of prepping for and undergoing colonoscopy.
"Ultimately," points out Dr. Semrad, "the right test will be different for different patients and different health systems."
