Current guidelines recommend screening for colorectal cancer in all adults 45 to 75 years old. If the screening is negative, patients don't need another one for 10 years.
CNN  — 

A new study raises the question whether some people can wait longer than the recommended 10years to repeat a colonoscopy after a negative initial screening for colorectal cancer.

The study, published in JAMA Internal Medicine, looked at 120,000 people 65 and older in Germany from 2013 to 2019 who had a colonoscopy 10 or more years after an initial negative screening, and it compared them with all colonoscopy screenings conducted on people 65 or older in that time period – most of whom were being screened for the first time.

It found the presence of precancerous or cancerous growths was 40% to 50% lower among the repeat screeners, finding advanced growths or cancers in only 4% to 5% of women and 5% to 7% of men 10 or more years after a negative colonoscopy.

The researchers also evaluated whether the number of abnormal growths differed between men and women, finding the prevalence 40% higher in men.

When looking by age, detection rates were highest among individuals 75 years or older.

The authors conclude that the current 10-year screening intervals for colonoscopies are safe, and they also suggest that extending the intervals may be warranted in some instances, especially for females and younger people without gastrointestinal symptoms.

“For instance, women at younger screening ages with no finding at index colonoscopy could possibly be screened at prolonged intervals or, alternatively, be offered less invasive methods, such as stool tests, while maintaining the 10-year interval for men and women at older ages,” the study authors wrote.

Current colonoscopy recommendations

Colorectal cancer is the second leading cause of cancer deaths in the United States. It is also one of the most preventable cancers with effective screening tests like colonoscopies that can detect early disease.

Death rates from colorectal cancer have decreased over recent decades, largely due to colonoscopies.

Current guidelines recommend screening for colorectal cancer in all adults 45 to 75 years old. The recommendations were recently changed to start screening at 45 instead of 50 years of age in response to more cancer being diagnosed at younger ages. If the screening is negative, patients don’t need another one for 10 years.

Dr. Douglas Owens, a health policy professor at Stanford University and a former chair of the US Preventive Services Task Force, which makes US cancer screening recommendations, said there is promise to the findings.

“(Colorectal cancer) is not like other cancers where there are big harms from over screening potentially. Here they are small, but they’re not zero, and it comes from the colonoscopy. So, if you could get the same benefit at a lower number of colonoscopies, that would be a win,” Owens said.

Owens would like to see more research on extending the screening intervals, as would Dr. Robert Bresalier, a professor of gastrointestinal oncology at MD Anderson Cancer Center.

“There’s good evidence that screening colonoscopy in asymptomatic individuals at 10-year intervals is effective and cost effective. And I think I’m not ready to change. I would not be ready to change practice in terms of extending the interval based on the study, but it is comforting and provides additional data to strengthen the concept of adhering to these guidelines,” Bresalier said. “The overall message from this study is we can feel comfortable with the current guidelines.”

The study authors note the study’s finding don’t extend to individuals who might need to undergo a colonoscopy at earlier intervals to assess symptoms they might be having, such as rectal bleeding, or individuals who are at higher risk of colorectal cancer. They say generalizing their findings should be done cautiously.

Experts maintain that colonoscopies are one of the most important preventive services and for all eligible groups to get tested.

“(This study) supports the importance of screening for colon cancer and that there are many ways, many effective ways to do that,” Owens said.

Although colonoscopy is considered the gold standard for colon cancer screening, there are alternatives. Other screening options include annual fecal occult blood tests which look for blood in the stool.

“The main thing is to get screened. It doesn’t matter if you use a stool test or you get a colonoscopy, pick one. Pick whichever one suits your preferences, but do it,” Owens said.

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More than a quarter of eligible Americans don’t get screened for colorectal cancer, and public health advocates urge Americans to get screened.

“Right now, the biggest impact we can have – and relevant to this discussion — is screening. So if you haven’t been screened and you’re in that age relevant group, you should get screened. And that clearly has a larger impact, and the biggest impact we can do right now in terms of influencing death of colorectal cancer,” Bresalier said.