- A New England Journal of Medicine study suggests colonoscopies aren’t as helpful as many had hoped.
- But health experts say the new study doesn’t change how doctors should think about colonoscopies.
- The Preventive Services Task Force recommends all adults 45 to 75 be screened for colorectal cancer.
For more than 20 years, American adults have been told to get colonoscopies beginning in middle age to prevent colon cancer.
But evidence supporting colonoscopy has never met the “gold standard” for research trials, so it’s been unclear exactly how useful the screening is for preventing cancer and saving lives.
A new study in European countries where colonoscopies weren’t routinely offered appears to suggest the procedure may be less helpful than many had hoped. But some health experts warn against misinterpreting the study’s findings.
“There’s a lot of nuances here, so it’s understandable that there are different takeaways from different folks,” said Dr. Chris Manz, a gastroenterology oncologist at Dana-Farber Cancer Institute in Boston.
What the New England Journal of Medicine study says
Takeaway: The report appears to show colonoscopies made little difference in rates of colon cancer detection and death, but that’s not the whole story.
In the study, more than 84,000 people ages 55 to 64 from Norway, Poland and Sweden were either “invited” to receive a colonoscopy or were given “usual care,” which in those countries involves no colon cancer screening at all. They were then followed for 10 years to see who developed colon cancer.
Only 42% of the 28,220 participants in the “invited” group actually had the procedure, compared to the approximately 56,300 participants who received “usual care” and did not get a colonoscopy.
When researchers checked a decade later, 259 people in the invited group had developed colon cancer and 622 in the twice-as-large usual care group. The death rates between the two groups were nearly identical.
But if all the participants randomly assigned to screen had actually undergone it, the risk of both developing and dying from colon cancer would have been cut by 50%.
What the health experts think
Takeaway: The new study doesn’t change how doctors think about colonoscopies.
The study says more about the propensity to get screened than it does about the procedure itself, experts say, as well over half of the “invited” group didn’t accept the invitation to get one.
“I don’t think this should change our practice,” said Dr. Robin Mendelsohn, a gastroenterologist at Memorial Sloan Kettering Cancer Center in New York City. “The bottom line is still get screened, still have the discussions” with your doctor.
Recommended colonoscopies are also more individualized in the U.S. – where uptake is more than 70% – compared to the study’s “invitation,” Manz said.
Is a colonoscopy the only way to screen for colon cancer?
Takeaway: Colonoscopies are the standard, but there are other options.
Although no one likes colonoscopies, due to the preparation and discomfort, they’re considered the best screening tool because they can detect and remove precancerous polyps.
In recent years, stool tests have gained in popularity because they can be done at home and don’t require prep.
“Stool tests are good at detecting cancer,” Mendelsohn said, but they don’t address precancerous growths and a positive test requires a follow-up colonoscopy.
What happens at a colonoscopy? Is it a painful procedure?
Takeaway: A colonoscopy is an exam to detect changes in the colon and rectum, and is one of the few options to screen for colorectal cancer, according to the Mayo Clinic.
During the procedure, a long, flexible tube with a tiny video camera at the tip is inserted in the rectum, allowing doctors to view the entire inside of the colon.
Colonoscopies take about 15 to 20 minutes and recovery is minimal with most patients’ sedation wearing off in about an hour, Manz said.
The procedure isn’t painful, he said, but some patients may experience bloating or gassiness.
When should you get a colonoscopy? And how often?
Takeaway: The Preventive Services Task Force recommends all adults 45 to 75 be screened for colorectal cancer.
Some people may need to begin testing earlier if they have an inflammatory bowel disease, a family history of certain conditions, or other factors that increase their risk of colorectal history, according to the Centers for Disease Control and Prevention.
Adults who aren’t at increased risk should get a colonoscopy every 10 years after their first screening, health experts say.
What are the risk factors for colon cancer?
Takeaway: Guidelines say the biggest risk factors include a family history of colon cancer, a genetic predisposition to cancer and a history of inflammatory bowel disease, radiation to the abdomen, or a history of precancerous polyps, Mendelsohn said.
Other risk factors may include obesity, smoking, drinking alcohol, engaging in less physical activity and eating a diet high in processed meat and low in vegetables.
Anyone who has persistent rectal bleeding, abdominal pain, or a change in bowel habits should be evaluated “promptly,” Mendelsohn said.
Experts say colon cancer is increasing among people under 40 for reasons that are not well understood. But still, the overall risk for colon cancer is small and falling, said Dr. Gil Welch, a senior researcher at the Center for Surgery and Public Health at Brigham and Women’s Hospital in Boston.
In the study, 1.2% of people who received no screening were diagnosed with colon cancer. Getting a colonoscopy reduced that risk to .8% – a 50% drop but still a small risk overall.
“We’re beginning to get a more realistic picture of the size of the effect of colonoscopies and it’s more moderate than advertised,” Welch said.
Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.
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