Cancer screening from the comfort of home
An alternative test for a colonoscopy proves as reliable
Most Americans who are due for a colon cancer screening will receive a postcard or a call — or prompting during a doctor’s visit — to remind them that it is time to schedule a colonoscopy.
But at big health care systems like Kaiser Permanente or the federal Veterans Health Administration, the process has changed. Patients who should be screened regularly (ages 50 to 75) and who are of average risk, get a letter telling them about a home test kit arriving by mail.
It is a FIT, which stands for fecal immunochemical test. The small cardboard mailer contains equipment and instructions for taking a stool sample and returning the test to a lab, to detect microscopic amounts of blood. A week or so later, the results show up on an online patient portal.
Five to 6% of patients will have a positive test and need to schedule a follow-up colonoscopy.
But a great majority are finished with colon cancer screening for the year — no uncomfortable prep, no need to skip work or find someone to drive them home after anesthesia, no colonoscopy.
Last spring, when the coronavirus pandemic closed many medical facilities and postponed nonemergency procedures, this approach suddenly looked even more desirable.
“We know that from March to May, colon cancer screenings fell by about 90%,” said Dr. Rachel Issaka, a gastroenterologist at the University of Washington and the Fred Hutchinson Cancer Research Center. Although testing has resumed, she said, “we’re still not back to where we were.”
Yet colon cancer represents the third highest cause of cancer deaths, after lung cancer and, tied for second place, breast and prostate cancer. Unlike those, colon cancer can be prevented with early detection.
An at-home test provides an alternative to colonoscopy — one that is both safer, with a lower risk of complications and COVID19 exposure, and does as good a job.
“If your doctor tells you a colonoscopy is better, that’s not accurate,” said
Dr. Alex Krist, chair of the U.S. Preventive Services Task Force, an independent expert panel that reviews evidence and issues recommendations. “The data show the tests are equally effective at saving lives.”
The task force is updating its guidelines for colon cancer screening and will probably recommend lowering the age at which it should begin, to
45. But the recommendations on the upper end will remain unchanged: Based on strong evidence, adults up to age 75 should be screened regularly.
Beyond that age, the disadvantages begin to mount. The task force says the benefit of screening 76to 85-year-olds is small, and that the decision should be an individual one, reached in consultation with a doctor.
Colon cancer develops slowly, said Dr. James Goodwin, a geriatrician and researcher at the University of Texas Medical Branch in Galveston. Patients at older ages, who typically contend with several other diseases, may not live long enough to benefit.
Although Americans still rely mostly on colonoscopy, his research has shown that for many older people, that test is overused, either because of the patients’ ages or because they are tested too frequently.
Yet screening is simultaneously underused. In 2018, according to the Centers for Disease Control and Prevention, only about 70% of adults were up-todate on colorectal cancer testing. About one-fifth of those 65 to 75 had not been screened as recommended. Among those 50 to 65, where lack of Medicare or other insurance probably contributed, only about 63% were appropriately screened.
The task force has found several kinds of screening tests effective, but the ones used most for people at average risk are colonoscopy, at a recommended 10-year interval, or FIT annually.
A newer entry, an at-home test sold under the brand name Cologuard that detects blood and cancer biomarkers in stool, may be used every three years, but a study found it to be less effective than most other methods and far more expensive than FIT.
Higher-risk patients — including those who have had colon cancer or parents or siblings with colon cancer, those with inflammatory bowel disorders, and those who have had abnormal previous tests — should seek out a colonoscopy. The procedure involves inserting a viewing instrument through the anus to directly visualize an anesthetized patient’s colon.
A colonoscopy offers one distinct advantage: If the gastroenterologist spots polyps, growths that over time could become cancerous (although most don’t), these can be removed immediately. “You’re preventing cancer, snipping out the things that could lead to cancer,” Goodwin said.
But the procedure’s complications increase with age, although they remain low. Cleaning out the bowel on the day before the procedure, in preparation, is disruptive and disagreeable, and Goodwin notes that older patients sometimes experience cycles of diarrhea and constipation for weeks afterward.
The FIT, which is far more widely used in other countries, avoids many of the difficulties of a colonoscopy. A marked improvement over earlier at-home stool tests, it requires a sample from one day instead of samples from three, and imposes no food or drug restrictions. A positive result still calls for a colonoscopy, but a great majority of patients avoid that outcome.
Why do so many Americans still undergo colonoscopies, then? “There’s a large financial incentive for people who do colonoscopies to do colonoscopies,” Goodwin said, so patients may not hear much about the alternatives.
Wider adoption of FIT could also save patients and insurers, notably Medicare, a boatload. The home test, which is available through several manufacturers, generally costs less than $20; a colonoscopy can easily exceed $1,000.