A review of more than 1.3 million Medicare patients aged 70 to 79 found that having a colonoscopy reduced colon cancer risk slightly over eight years, from just under 3 percent to a little more than 2 percent in those younger than 75. But it had little or no effect on cancer risk among patients over 75.
However, Robert Smith, vice president for cancer screening at the American Cancer Society, said it would be misguided to stop all colonoscopies for people once they turn 75. The better criterion is the overall health and life expectancy of the patient, he said.
"The issue is with older adults whether or not there is any benefit for screening. After 75, you can make individualized decisions [about] whether screening is appropriate," said Smith, who was not involved in the study.
Screening guidelines from the U.S. Preventive Services Task Force recommend screening for colon cancer with any method, including colonoscopy, from age 50 to 75. Medicare reimburses colonoscopy, regardless of age.
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Smith said the people in this study were in good health. But, in practice, people with limited life expectancy are also being screened, which is not recommended, he said.
Study lead author Dr. Xabier Garcia-Albeniz, a research associate at the Harvard School of Public Health, and colleagues noted that colonoscopy is an invasive procedure that requires a thorough bowel cleansing and often sedation beforehand. Risks of complications include bowel perforation during the procedure.
However, the study authors found that the risk for serious harm from colonoscopy was small in both age groups.
"Patients, physicians and policymakers may want to consider these findings when making decisions about colorectal cancer screening, especially in upper age groups," the researchers said.
The report was published Sept. 26 in the Annals of Internal Medicine.
Smith said: "Healthy older people benefit from screening. But you're not going to benefit if you are likely to die from something else. If you have colon cancer but are likely to die before there are symptoms, then screening doesn't help very much."
The challenge, he said, is how to determine if the patient is going to live much longer.
Often people get to 70 or 75, and they have common chronic health conditions such as high blood pressure or high cholesterol or diabetes that won't alter their life expectancy. Yet their doctor "may think they are too old to benefit from [colonoscopy] screening, but they may live another 10 to 20 years," Smith said.
Smith doesn't believe colonoscopy is the only way to screen for colon cancer. Other methods, such as fecal occult blood test or a CT colonoscopy, are noninvasive and can be accurate as well. Scanning the colon is noninvasive, he said, and although it is not covered by Medicare, it is recommended by the Preventive Services Task Force.
"How we screen older adults is an area that needs further investigation beyond, 'Are they going to benefit from colonoscopy or not?' " Smith said.
Visit the American Cancer Society for more on colon cancer.
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