Colon cancer screening may be safe every 15 years for some, research suggests

New research suggests that patients at average risk for colon cancer may only need to undergo colonoscopy screening every 15 years instead of the recommended 10 years.

Swedish researchers found that waiting an additional five years after a first negative colonoscopy carried about the same risk of later having a colorectal diagnosis or dying from the disease as being screened every 10 years. Extending screening time could reduce “unnecessary invasive examinations,” according to the study published Thursday in JAMA Oncology.

Colorectal cancer is the fourth most commonly diagnosed cancer in the United States and the second most deadly behind lung cancer. The American Cancer Society recommends that screening begin at age 45 for people who do not have a family history of colorectal cancer or other risk factors, such as inflammatory bowel disease.

In an editorial accompanying the new study, gastroenterologists suggested that future screening guidelines could be safely extended for some people, noting that “15 has the potential to become the new 10.”

While rates are decreasing among people over 50, colorectal cancer diagnoses are increasing among younger people, paving the way for a potentially large new group of people who may require colonoscopies.

Doctors are wondering how to best distribute appointments.

“We don’t have enough gastroenterology doctors to do a colonoscopy every 10 years in everyone over 50,” Dr. Otis Brawley, Bloomberg Distinguished Professor of Oncology and Epidemiology, told Johns Hopkins University, which was not associated with the new research.

For the new study, researchers looked at national registry data from more than 110,000 people whose first colonoscopy came back negative for colorectal cancer. They compared these people to more than a million in a control group.

The average age in both groups was 59 years and approximately 60% of patients were women. Controlling for family history, they found that after a negative first colonoscopy, the risk of later being diagnosed with colorectal cancer or dying from the disease was about the same among people who had a colonoscopy every those aged 10 and those who had extended it up to 15 years. .

They estimated that waiting an additional five years between colonoscopies would miss two cases of colorectal cancer and result in one colorectal cancer-related death per 1,000 people, while potentially saving 1,000 colonoscopies for other patients.

Employing less expensive and less invasive screening methods 10 to 15 years after a negative colonoscopy could significantly reduce the number of missed screenings, said the study’s lead author, Dr. Mahdi Fallah, head of the prevention group. of risk-adapted cancer at the German Cancer Research Center in Heidelberg.

“The best screening test is the one that is actually performed. So if a test like colonoscopy is unaffordable for a person, another valid, less expensive test is much better than no test at all,” said Fallah, who is also a visiting professor in the Department of Clinical Sciences at the Lund University in Sweden.

A more diverse population

The research was conducted in Sweden, which has a predominantly white population and a healthcare system very different from that of the United States. The National Health System also collects information on the family medical history of its citizens, meaning researchers can be sure those who reported no colorectal cancer in their family were correct.

“It would be very difficult to apply these results to the United States,” said Dr. Cassandra Fritz, a gastroenterologist at Washington University in St. Louis. “When we ask patients about colorectal cancer in first-degree relatives, most people don’t know.” Fritz was not involved in the new study.

The United States is also much more racially and ethnically diverse, but the research provides important context that will help doctors understand how they can best delegate their limited resources, Fritz added.

“We need to think about how we can potentially save resources and impact more people with the resources we have,” said Dr. Andrew Chan, gastroenterologist and director of epidemiology at Massachusetts General Cancer Center in Boston and co-author of JAMA. editorial.

The proportion of colorectal cancers occurring in people under 55 doubled between 1995 and 2019, from 11% to 20%. But the total number of cases in this population remains relatively low.

“Once you’re under 50, cases of colorectal cancer probably won’t require screening in everyone. The risk-benefit does not exceed the cost,” Dr. Robert Bresalier, professor of medicine in the department of gastroenterology, hepatology and nutrition at the University of Texas MD Anderson Cancer Center at Houston. Bresalier was not involved in the new research.

This only applies to people with no family history, he added. People whose parent or sibling has had colorectal cancer should begin screening 10 years before that parent or sibling is diagnosed, Brawley said.

Other means of screening, mainly stool tests, have been improved in recent years to be more precise. Fecal occult blood tests detect blood in the stool, which can be a warning sign of colon polyps or cancer. FIT-DNA tests, such as Cologuard, detect altered DNA in stool, which could indicate cancer, and are about 90% effective at detecting cancer, but are less effective at detecting precancerous polyps.

These tests are non-invasive and relatively inexpensive compared to colonoscopy screening. The problem is that they need to be done more often – every one to three years – than colonoscopy. If the test is positive, the person should have a colonoscopy, which could trigger a colonoscopy sooner than every 10 years.

Still, the tests could be a good option to reduce the number of colonoscopies performed after an initial negative screening, Chan said.

“It’s important to get tested, but there are a limited number of resources to screen people,” he said. “To screen as many people as possible, we need to make choices about what type of screening we do and how often we do it. »

In the United States, better screening will likely be more tailored to risk factors other than age, about which experts don’t yet know much, Bresalier said.

“One solution may not fit everyone. We know a lot about the genetics of colorectal cancer, but most of this research has been done on white people. There are potential differences between men and women and between different ethnicities,” he said. “We might get to a point where we get to risk-based intervals, even in people at normal risk, based on these other factors.”

Warning signs of colon cancer

Symptoms of colorectal cancer often do not appear until later stages and can be difficult to differentiate from other less serious conditions.

“You can’t rely on symptoms,” Chan said. “Many people have no symptoms, which highlights the importance of testing. »

The presence of blood in the stool, which may appear red or black, a change in how often you go, abdominal pain and weight loss can all be warning signs of colorectal cancer – and they can also be signs of irritable bowel syndrome, inflammatory bowel disease. and a host of other less serious problems.

Still, people with new symptoms should make an appointment with a doctor, Fritz said.

Everyone over the age of 45 should start getting tested. What that looks like may be determined by where you live.

“In some areas it is easier to get a colonoscopy than in others. In some areas, it might be more realistic to do a stool-based test,” Chan said.

This includes people living in rural areas or areas without access to a gastroenterologist. For those who are underinsured or uninsured, Fritz said it is possible to pay cash for a stool test, although a positive stool test will require a colonoscopy later.

Something everyone should do is understand their risk, Fritz said.

“Many people avoid having conversations about bowel movements, but it’s very important to talk to your family to find out if you are at high risk,” she said.