To detect colorectal cancer, many people can safely skip a colonoscopy in favor of this once-a-year, easy-to-use test, according to a new study review.

By Amanda MacMillan
Updated February 26, 2019

The colonoscopy might be the most dreaded of all health screenings. Uncomfortable and intrusive, it can be a literal lifesaver—but currently, only 60% to 65% of adults who should be up to date on this important test actually are. The procedure, in which a long, flexible tube is inserted into the rectum, detects signs of (or precursors to) colorectal cancer, the second leading cause of cancer-related death in the United States.

Most health organizations recommend that a colonoscopy be performed at least once every 10 years starting at age 45 or 50. But studies in recent years have suggested that a less expensive, less invasive, at-home stool screening may be as effective as colonoscopy at detecting cancer. And now, researchers say, a review published this week in the Annals of Internal Medicine provides the strongest evidence yet that many patients can safely forego colonoscopy in favor of this once-a-year, easy-to-use test.

RELATED: Colorectal Cancer Screenings Should Start at 45, New American Cancer Society Guidelines Say

Known as fecal immunochemical tests (FIT), these at-home kits analyze stool samples and identify hidden blood that could be a sign of cancer. For the new review, researchers from Indiana University School of Medicine and the Regenstrief Institute in Indianapolis combed through the findings of 31 previous studies involving 120,255 participants, all of whom were given an FIT and then a subsequent colonoscopy.

When the results were combined and analyzed as a whole, the researchers found that about a third of patients who received positive results on their FIT were found to have colorectal cancer or an advanced precancerous polyp. What this means, the researchers say, is that FIT can be a good “pre-screening” test for adults who are at average risk and have no symptoms, and can save people the hassle and costs of more complicated testing.

“If annual FIT results remain negative, FIT buys you time until colonoscopy may be required,” said lead author Thomas Imperiale, MD, professor of gastroenterology at Indiana University School of Medicine, in a press release. “And it could be the case that a colonoscopy for screening may never be necessary or required.”

RELATED: The Rectal and Colon Cancer Symptoms You Need to Know, Even if You're Young

According to an editorial published with the review, colonoscopy is considered the gold standard for colon cancer screening in the United States; it’s also the most frequently used screening method, and is often given to healthy adults with no symptoms or risk factors. But in several other countries, the test is only performed if a patient’s FIT results are positive.

“It should be reassuring to skeptics that most countries with [colorectal cancer] population screening programs use FITs as their test of choice,” wrote editorial author James Allison, MD, a professor emeritus at the University of California, San Francisco. “For example, in Canada, a positive FIT result is mandatory in an average-risk patient before colonoscopy is covered by insurance.”

FIT is also considered an effective pre-screening in the United Kingdom and Italy, as well, according to the review. A similar approach could be safely adopted in the United States, says Dr. Imperiale. But a better system to actually get people tested (and ensure they get a follow-up colonoscopy, if their FIT is positive) is still needed, he points out. “We need a system that is population-based rather than the current opportunistic one,” he said in the press release, noting that poor, uneducated, and uninsured patients are often left out.

In 2018, the American Cancer Society updated its colorectal cancer guidelines, recommending that screening start at age 45 (instead of 50) and continue through age 75 or 85, depending on patient preference and prior screening history. The options for screening, according to these guidelines, include colonoscopy every 10 years, a fecal blood test (such as FIT) every year, or various other procedures (a stool DNA test, colongraphy, or flexible sigmoidoscopy) every 3 to 5 years.

In his editorial, Dr. Allison stresses that it’s important for doctors to see FIT as equal to colonoscopies, and not as a second-rate test. “Physicians in the United States must understand the advantages of FITs as screening tests for [colorectal cancer] and educate and advocate to increase screening rates,” he wrote, “especially in vulnerable populations."

RELATED: What It Was Like to Be Diagnosed With Colorectal Cancer When I Was 28 Weeks Pregnant