17 june 2009-- Screening colonoscopies for colon cancer may be too risky for some elderly patients, a new study finds.
Of all the screening methods for colon cancer, a colonoscopy is considered the gold standard because it not only finds, but also removes, cancerous and precancerous lesions. However, risks such as bleeding, colon perforation and heart problems, while low, may outweigh the benefits for some elderly patients.
"Overall, the risks from colonoscopy are quite low," said lead researcher Joan L. Warren, of the Applied Research Program at the U.S. National Cancer Institute. "However, there are some groups of people for whom the risk was significantly elevated."
They are older people and those with a history of stroke, diabetes, heart failure and atrial fibrillation, Warren said. "For people 85 and over, risk is more than twice that of people 66 to 69. For people 80 and over, the risk is about 50 percent greater," she said.
Older adults with these risk factors need to evaluate the risk of screening colonoscopy against their life expectancy, Warren said.
Colon cancer screening is important for identifying the disease in its earliest, most treatable stages. For people with risk factors for a colonoscopy, Warren suggests less-invasive tests such as the fecal occult blood test.
"Somebody who is older and not in great health might benefit from a fecal occult blood test, and if the result is positive then a colonoscopy may be needed," she said.
The report is published in the June 16 issue of the Annals of Internal Medicine.
For the study, Warren's team collected data on 53,220 Medicare recipients who had colonoscopies between July 2001 and October 2005. The researchers compared these patients with a matched set of Medicare beneficiaries who did not have colonoscopies.
The researchers looked for claims made to Medicare for bleeding, perforation of the colon and heart problems resulting from the procedure.
Warren's group found that those undergoing colonoscopy had a greater risk of adverse events than those who did not have the procedure. The rates of these problems increased with age, the researchers noted.
Moreover, patients who had a polyp removed during the procedure had a higher risk for adverse events than those without polypectomy.
Patients with a history of stroke, chronic obstructive pulmonary disease, atrial fibrillation or congestive heart failure -- or multiple chronic conditions -- had a higher risk for bleeding and colon perforation, the researchers found.
Dr. Thomas Imperiale, a professor of medicine at Indiana University Medical Center in Indianapolis, said these findings will help clinicians better tailor the risks of colonoscopy to their patients.
"In addition to describing to patients an average, overall risk, we can be more precise in our explanation of perforation risk, based on the patient's age, their medical conditions, the indication for the colonoscopy and whether a polyp is removed," he said.
"Providers need to be thoughtful about assessing the benefits and risks of colonoscopy for every patient and for any indication, but especially for screening, where there is arguably less potential for benefit than for a diagnostic or therapeutic colonoscopy," Imperiale said.
Another expert says the study demonstrates that colonoscopy, even among the elderly, is generally safe and should not be discounted on age alone.
"One should be cautious about interpreting this data without putting it into the context of the potential benefits to the patients," said Dr. George Chang, an assistant professor of surgical oncology at the University of Texas M.D. Anderson Cancer Center.
The patient's overall health and life expectancy should really determine the appropriateness of colonoscopy among the elderly, Chang said. "Age alone should probably not be used for the determination of the appropriateness of colorectal cancer screening," he said.
Dr. Durado Brooks, director of prostate and colorectal cancer prevention programs at the American Cancer Society, thinks the study raises questions about the recent decision by the U.S. Centers for Medicare & Medicaid Services not to pay for so-called virtual colonoscopies.
"Given the possibility of harm coming to patients [from colonoscopy], it seems ill-advised to withhold another potential screening approach that would allow physicians to have a complete view of the patient's colon," Brooks said.