Colonoscopy: The Truth About That 10-year Follow-up Colonoscopy (Part 4)

Researchers delving into the timing of subsequent colonoscopies found that for some people, the risks are no different if they wait 15 years instead of 10.

The invasive and expensive nature of colonoscopies makes determining how to maximize their usefulness—particularly when it comes to follow-up screenings—a prominent topic of research. It’s undisputed that the surgical-based test can save lives, but the timing remains a moving target.

Three years ago, the U.S. Preventive Services Task Force lowered the recommended age for the first colorectal cancer screening by five years—from 50 years of age to 45. Now, the gap between the first and second tests is being scrutinized.

Long-term data used in a JAMA Oncology study published May 2, 2024 suggests it may be time to move the follow-up screening back five years in certain circumstances. Specifically, the study indicates that anyone who doesn’t have a family history of colorectal cancer and whose first colonoscopy was free of polyps—abnormal tissue growth that can lead to cancer—could have their second screening test in 15 years, rather than the current recommendation of 10 years.

More than 152,000 people in the United States are expected to be diagnosed with colorectal cancer this year, and an estimated 53,010 will die, according to the Colorectal Cancer Alliance. It’s the second-leading cause of cancer deaths but one of the most preventable.

“What we know about colon cancer is it’s very slow growing. Screening for it is never urgent, but it’s very important because we can diagnose it very early,” Dr. Carl Bryce, a family physician, told The Epoch Times. “The sooner the treatment, the much better the outcomes.”

The reasoning behind 10-year screenings is that it takes about that long for polyps to transform into tumors. The test is invasive, comes with risks, and is costly—all reasons researchers continue to study whether the timeline can be expanded. In the new study, a statistical analysis found waiting 15 years in between screenings brought minimal risks.

Proceed With Caution

However, that doesn’t mean everyone should wait 15 years before a second screening.

The finding is a bit nuanced, not to mention entirely unofficial—two reasons Dr. Cedrek McFadden of the Colorectal Cancer Alliance medical scientific advisory committee has concerns about the study. The alliance’s mission is to raise screening rates, improve survival rates, and invest in research to end colorectal cancer.

While an accompanying JAMA editorial offered an enthusiastic perspective for the proposed change to 15 years between screenings, the recommendation hasn’t been adopted by any U.S. organizations that set guidelines for colorectal cancer screenings such as the U.S. Preventive Services Task Force, American College of Gastroenterology, or American Cancer Society.

Additionally, Dr. McFadden noted the study was conducted in Sweden—meaning it may not hold true in the United States. He’s also concerned about narrow qualifications being misconstrued by the media or overlooked by patients who make decisions based on “headlines” or social media content, rather than conversations with their doctors and official guidelines.

“If it sounds like I’m not ready to take up this recommendation, that’s absolutely true. I don’t think this is a study that is generalizable to the patients I take care of,” Dr. McFadden, a board-certified surgeon specializing in the large intestine, told The Epoch Times. “While it’s worthwhile to look into, I don’t think it’s ready for prime time.”

Family History Matters

Family history remains one of the biggest risk factors for colorectal cancer, which is why anyone who’s had a family member affected should begin screening for the disease before the recommendation at age 45. Those with an immediate family member with colorectal cancer have a two to four times greater risk of developing it themselves.

The JAMA study recommendation not only considered family history but confirmed there is a lower risk for people without an immediate family member affected by colorectal cancer.

The study examined 29 years of patient data going back to 1990, looking at a group of 110,000 patients in a Swedish database who had no family history of colorectal cancer and had initial colonoscopies with negative results—meaning they had no diagnoses of polyps, cancer, or adenoma, benign tumors.

They were then each compared to 18 age-matched controls of the same gender who also had colonoscopies with negative results.  For the first 10 years, the risk of colorectal cancer and colorectal cancer death were lower by 72 percent and 55 percent respectively in the group with no family history and negative findings.

Ten-year statistics were the baseline for determining risk at the 15-year mark and every year afterward up to 20 years. Researchers found that 2.4 more cases of colorectal cancer per 1,000 people may be missed by extending the screening interval to 15 years. That rate jumped to 4.5 more per 1,000 at year 16 and increased gradually to 11.9 additional cases per 1,000 people by year 20.

Colorectal cancer deaths had a similar but less steep trend. The statistics showed a possible 1.4 additional deaths per 1,000 people by extending colonoscopies to 15 years from 10 years. At year 16, the rate increased to two more deaths per 1,000 people, and at 20 years, the rate was 3.6 additional deaths per 1,000.

The authors noted that “almost 1,000 colonoscopies per 1,000 individuals could be avoided. Therefore, our recommendation of a 15-year colonoscopy screening interval would avoid many invasive colonoscopy examinations with a minimal toll.”

Most at Risk

Though colorectal cancer has a high survival rate when it’s discovered early, Dr. Bryce noted that not much is known about those people who develop colorectal cancer in between screenings.

“It is a bit of controversy lately regarding the screening intervals and how much time is the right spot because certainly there are interval cancers that develop between the screenings,” he said. “It takes many years to study, and they don’t really know yet.”

Dr. Bryce, who is among a small percentage of family doctors who also perform screening colonoscopies, once had a younger patient come in for his first test and end up with a cancer diagnosis that same day. He encourages his patients to get at least one screening.

Beyond that, it’s a complicated decision that blends agreed-upon factors—like stopping colonoscopies at age 75 or when the patient’s life expectancy is under 10 years—with more nuanced “timing that makes sense for the patient,” Dr. Bryce explained.

He uses the American Gastroenterology Association’s guidelines published in 2020 in the journal Gastroenterology as a template. It includes flow charts that factor in patient age, size and number of polyps, family history, and other considerations to determine follow-up screenings.

“It’s a multi-specialty guideline that looked at all the studies and approaches. Ultimately what they decided on is a consensus interval,” Dr. Bryce said. “There’s still some answers out there we need to find. Does it improve mortality? Does it save lives? We think so, but the research is still ongoing.”

More Conversations

Those guidelines acknowledge a plethora of complications—including gaps in research and evolving knowledge that shows lengthening the time between screenings is becoming more common, particularly for patients with only one or two small polyps. They note that it can be emotionally difficult for physicians and patients to bump back appointments, particularly those made before the guidelines changed. They have the option to discuss it and decide on which timeline is best.

“Evidence to support best practices for surveillance colonoscopy has strengthened and has helped to support close follow-up for some groups, as well as less intense follow-up for others,” the guidelines state. “More work is needed to fully understand which patient populations are most likely to benefit from surveillance, and the ideal surveillance interventions to apply for optimizing [colorectal cancer] prevention and early detection.”

Because of the confusing and changing nature of guidelines, Dr. McFadden said not only do doctors and patients need to talk to one another more, but patients also need to have conversations with family, too.

He noted that his patient population is oftentimes unaware of their family history.

“The individualized nature of colon screenings is unique. In many ways it may be as unique as your fingerprint,” he said. “A part of that is knowing your history and your family’s history. We have to encourage our families to speak up and tell the stories of the health of the other family members, of our own health so we can all make better choices and have more information when we’re making these decisions.”

Beyond Colonoscopies

There are tools other than colonoscopies to detect colorectal cancer—including stool studies. While colonoscopies are common in the United States, other countries tend to lean more on stool and even blood testing to screen for colorectal cancer.

Those tests identify hemoglobin proteins, DNA biomarkers, and blood. There are also virtual colonoscopies using CT scans to determine whether there are polyps or abnormalities in the colon.

Those tests should be considered in light of the invasiveness of colonoscopies, according to a 2022 review in Nature Reviews Gastroenterology and Hepatology, as well as the fact that only 67 percent of U.S. patients are “up to date” on colonoscopies.

“There is an unfulfilled need for multiple-modality [colorectal cancer] screening that can improve current [colorectal cancer] screening rates. Newer technologies might be resource-effective strategies when used to select patients for colonoscopy,” the article stated.

Controlling What You Can

Dr. McFadden said doctors and patients should expect changes but to be mindful about how they get information and make decisions. He envisions in five or 10 years, there could be microbiome tests that can screen for colorectal cancer. The gut microbiome—measured through stool samples—includes all the bacteria, viruses, and fungi believed to be living in the colon.

A February 2023 article in Neoplasia said those with colorectal cancer have a loss of microbial diversity and “microbiome changes can already be observed in very early stages” of colorectal cancer. But it’s still a hypothesis that a microbiome test could be a biomarker.

The microbiome is associated with diet, which is why Dr. McFadden discusses eating habits with his patients. Colorectal cancer is becoming more common at younger ages, and it impacts black Americans at a higher rate.

Beyond family history, risk factors for colorectal cancer include:

• Inflammatory bowel disease—both Crohn’s disease and ulcerative colitis
• Diet—ultra-processed food, excessive and processed meat, alcohol, and low fiber
• Smoking
• Radiation exposure
• Age

“What we put into our bodies is definitely one of those things we can control and these are conversations I have with my patients,” Dr. McFadden said. “Really limiting the food options that don’t help us and making them more the exception than the rule for our consumption, and maintaining a healthy weight for our bodies can be helpful.”

How Colonoscopies May Harm Gut Health—and How to Help

It’s common after a colonoscopy to feel symptoms such as gas, bloating, stomach pain, and cramping. For some people, the symptoms can go on for weeks and cause permanent changes to the gut microbiota.

About 40 percent of patients may experience these lingering problems, which tend to be more common in women, patients who have a longer procedure time, and those with preexisting diseases that already disrupt the microbiota, such as inflammatory bowel disease (IBD).

Changes in the gut microbiota—bacteria, viruses, fungi, and other microorganisms that live mainly in the large intestine—drive general gastrointestinal (GI) discomfort. Colonoscopies can cause negative microbial population shifts, called dysbiosis, although the effects are short-lived for most people.

Colonoscopy timing and microbial recovery efforts, such as eating a healthy diet and taking probiotics, may be key to avoiding or shortening this period of GI distress.

Why Colonoscopies Deplete Microbes

Laxatives, rapid defecation, depletion of the colon’s mucosal layer, and exposure to oxygen during the procedure could all drive changes in a person’s microbiota, according to a 2024 review in Clinical Endoscopy.

Diarrhea is associated with dysbiosis secondary to a change in the mucus thickness of the colon. Although thinning of the mucus can offer gastroenterologists—or physicians who diagnose and treat disorders of the gastrointestinal tract—a better view of polyps and problem areas during a colonoscopy, authors of the review noted that thinner mucus results in a decrease of the beneficial bacteria Akkermansia.

Bowel prep can cause a significant alteration of gut microbiota, at least initially.

“Most studies have reported that the gut microbiota composition returns to the baseline within two to six weeks after colonoscopy, suggesting the resilience of the gut microbiota,” the authors wrote.

Some studies report no significant changes in the gut microbiota after colonoscopy. Of note, in studies reporting dysbiosis, certain factors tended to be associated with dysbiotic trends, such as baseline gut microbiota status, predisposing factors such as IBD and being overweight, and bowel preparation methods.

Splitting up the doses of bowel preparation—typically half on the night before and half on the morning of the procedure—was associated with better microbial recovery.

“Interestingly, that is what is advocated as the standard of care right now for bowel preparation because it does a much better job also in cleaning the bowel prior to colonoscopy rather than taking the whole preparation at once,” Dr. Andres F. Carrion, a gastroenterologist and spokesperson for the American Gastroenterological Association (AGA) told The Epoch Times.

Research shows that using carbon dioxide rather than a mixture that includes oxygen is better for microbiota. The air expands the colon, giving surgeons a better view during the procedure.

Restoring Gut Flora

Colonoscopy recommendations do not include guidance on how to restore the microbiota. However, research—including the Clinical Endoscopy review—shows that probiotics are helpful for at-risk patients.

Studies show varying results. In some studies, probiotics are given before the procedures, although most studies investigate post-colonoscopy probiotic use. In general, probiotics can increase the overall diversity of the gut flora.

Various mixtures of Bifidobacterium infantis, Lactobacillus acidophilus, Enterococcus faecalis, and Bacillus cereus present in probiotic preparations promote a rapid decrease in Proteobacteria, which can be disease-protective.

Probiotics offer great benefits to individuals who experience gastrointestinal symptoms before a colonoscopy, according to the review.

Although the authors stated that it’s unclear whether there is a benefit for the general population, a new meta-analysis of probiotics used after colonoscopy highlighted at a recent AGA conference showed a more widespread benefit.

Specifically, it found statistically significant reductions in bloating, pain, and vomiting among those who took probiotics compared with those who didn’t take probiotics in a study involving 2,345 patients. Modest reductions were also reported for nausea, constipation, gas, and diarrhea.

“These findings underscore probiotics’ potential to enhance patient experiences and may, in turn, encourage more patients to undergo future colonoscopies,” the authors wrote.

Diet Can Help or Hurt

The bigger problem, Carrion said, is that most patients will return to their normal diet right after a colonoscopy. For most people, it’s an unhealthy mix of processed and fast foods.

It’s also important for patients to properly prepare for the procedure by avoiding food and sticking to a diet of clear liquids. Improperly following instructions can result in incomplete preparation of the colon. This incomplete preparation can result in discomfort, an ineffective procedure, or the need to reschedule the procedure.

“I think what’s more important than probiotics is to get the patient into a diet that’s prebiotic, which is fiber. I tell patients that’s the fertilizer for microbes to help them rebuild their own microbiome or flora with the help of healthy foods,” he said. “My take is that’s probably going to work better than putting everyone on a probiotic after a colonoscopy.”

In other words, probiotics and prebiotics such as fiber should be long-term solutions, not quick fixes taken only before colonoscopy.

Prebiotics are food for gut bacteria found in fiber-rich carbohydrates. Probiotics are bacteria naturally occurring in some food that can help replenish the microbiota.

Prebiotic foods include:

• Fruits and vegetables such as garlic, onions, asparagus, and bananas
• Grains and legumes such as wheat, flaxseeds, peas, and beans
• Dark chocolate

Probiotics are found in foods typically fermented, such as yogurt, sauerkraut, kimchi, and kefir. Newer functional foods also have probiotics added to them; more information on these can be found in the Alliance for Education on Probiotics guide.

It’s also important to avoid a high-sugar, high-fat diet, according to Carrion.

He said he has found three barriers that keep his patients from opting to eat healthier diets: time, money, and interest. The increased desire to rely on processed and fast foods will continue to drive dysbiosis, Carrion said.

“Everyone wants a pill,” he said. “I think society has gone the wrong way completely in relation to dietary habits. We’re not making any more progress as the years go by. Some people are pretty much not interested in changing their dietary habits.”

References:

https://www.theepochtimes.com/health/about-that-10-year-follow-up-colonoscopy-5656067

https://www.theepochtimes.com/health/why-your-colonoscopy-may-worsen-gut-health-and-what-to-do-about-it-5828989

This article is part of the series on colo-rectal cancer. Check out the other articles: Colo-rectal Cancer series