When to get your next colonoscopy
The colorectal cancer mortality rate in the United States is down more than 50% from what it was two decades ago, when doctors started using the colonoscopy more as a screening tool than a diagnostic tool.
Colonoscopies can also be tools for prevention, by removing pre-cancerous polyps. The general consensus in American medicine is for people to get their first screening colonoscopy at age 50, or sooner depending on ethnicity and family history.
Now, three gastroenterology subspecialty societies have issued unified guideline recommendations for what to do after that first colonoscopy.
The recommendations vary based on what turns up in the colonoscopy—what types of growths are found, how many, and how large.
"What you find here now is, we are doing a better job of risk-stratifying the timing of your next colonoscopy, based on the findings of your current colonoscopy," says Dr. John Birk, chief of UConn Health's Division of Gastroenterology.
For example, for someone who has three or four growths known as tubular adenomas that measure less than 10 millimeters (1 centimeter), the recommendation would be to come back for another colonoscopy in three to five years. A single tubular adenoma considered "advanced," measuring 10 millimeters or more, would lead to a recommendation of three years. If no adenomas are found, the recommendation is 10 years.
"People who have one or two of these small tubular adenomas, less than a centimeter, now really can go longer, with the guidelines now saying seven to 10 years, so you probably can go at least seven years instead of five years until your next colonoscopy, where we used to say five years," Birk says.
If the colonoscopy turns up a growth known as a sessile serrated polyp (SSP), the recommendations are for an earlier follow-up colonoscopy. Less threatening is what's known as a hyperplastic polyp found in or near the rectum. If they're small enough—less than 10 millimeters—it would take more than 20 of these polyps to become worrisome.
"If you have pure hyperplastic polyps, it's probably low-risk and you probably can wait 10 years," Birk says. "However, now, if you have a sessile serrated polyp, you're at a little increased risk, and we've shortened the interval for your next screening."
Despite having a colonoscopy, you still can develop a cancer before your next one, which is what's known as an interval cancer. Identifying those patients who are at higher risk to develop something malignant in the interval between screenings allows doctors to appropriately decrease the interval time between colonoscopies and minimize that risk.
"Depending on what that first colonoscopy shows, it will tell us if you're a 10-year person or a three-year person," Birk says. "Now, family history can dictate your course no matter what the findings are, but these new guidelines bring an added nuance to it."
Family history still rules. The updated guidelines apply to adults considered "average risk" and do not negate family history when it comes to recommending screening intervals, Birk says. For example, if you have a family member who had a colon cancer diagnosis or significant polyp before age 60, you still would come back in five years, even if your first colonoscopy found nothing.
The new guidelines come from a collaboration of the American Gastroenterological Association, the American College of Gastroenterology, and the American Society for Gastrointestinal Endoscopy. One of the contributors is Dr. Joseph Anderson, formerly of UConn Health, who retains a faculty appointment at the UConn School of Medicine and still collaborates with Birk.