COVID-19 increases allure of at-home colon cancer tests

Colonoscopies dropped by 90% last year and still have not returned to pre-pandemic levels.

A year ago, when the COVID-19 lockdown began, Dr. Rachel Issaka expected that colonoscopies would decline. She was surprised by how much.

In the first two months, in-clinic colon cancer screenings fell by 90%.  "I was shocked," said Issaka, a UW Medicine gastroenterologist and researcher with the Fred Hutchinson Cancer Research Center.

There has, however, been a substantial comeback in these screenings: The difference between now and last March is just 15%. People with a family history of colon cancer are again booking appointments, Issaka noted. Others are taking an at-home test first and, if an abnormal result is detected, following up with a colonoscopy. A third group, mostly with no medical history of colon cancer, are waiting until they are fully vaccinated.

“Screening rates will likely return to pre-pandemic levels. What is less certain is how the split between screening colonoscopies and at-home stool tests will look like post-pandemic," she said.

Two commonly used stool-based screening instruments are the fecal immunochemical test (FIT) and the FIT-DNA test. The FIT  tests for blood in the stool and its findings are accurate about 79% of the time.  The FIT-DNA test – one such product is Cologuard – tests for blood in the stool as well as abnormal DNA. It is accurate 92% of the time but has a higher rate of false positives than the FIT. Regardless of which test is used, an abnormal result necessitates a colonoscopy, Issaka said. 

For now, it is recommended that patients complete a FIT test annually, while the FIT-DNA test is recomended only once every three years if the result is normal. 

A colonoscopy makes more sense for people with a family history of colon cancer, or who are experiencing new, unexplained abdominal pain, changes in stool diameter, unexplained weight loss or blood in the stool.

Getting screened is especially important for people with a family history and for Black patients, who have relatively poor outcomes with colon cancer, Issaka said. In the United States, Black people are 20% more likely than non-Hispanic white people to be diagnosed with the disease and about 40% more likely to die from it. In general, colon cancer accounts as the third-highest cause of cancer deaths, after lung cancer and breast and prostate cancer (tied at No. 2.)

Colon cancer, if diagnosed at an early stage, has a five-year survival rate of 90%. Yet it is estimated that only 65% of the U.S. population actually follows screening recommendations. Offering an at-home test increases colon-cancer screening participation by 22%, according to a 2018 study that Issaka led.

The question of when you should begin colon cancer screening, either at home or in the clinic, is a moving target, she said.

The U.S. Preventive Services Task Force reviewing a draft recommendation that would lower colorectal cancer screening age to 45-49.  It is based on evidence that colorectal cancer incidence in 45-year-old adults now approaches that of 50-year-olds when screening guidance was first issued in the 1990’s. The American College of Gastroenterologists also just recommended that colon-cancer screenings begin at 45.

As the number of vaccinated people increases, Issaka encourages individuals who are hesitant to consider the safety the the gold-standard, in-clinic colonoscopy. However, it is most important, she said, that everyone ages 45 to 50 pursue some screening, even if it starts with a test at home.

“Screening is necessary even during COVID-19.  The pandemic is no reason to delay this very important care,” she said. 

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