New colorectal cancer screening guidelines released

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New colorectal cancer screening guidelines push for adults 50 and older to get screened — somehow

June 16, 2016
Colon carcinoma

Several colorectal cancer screening options are now available — and recommended — by the U.S. Preventive Services Task Force, including DNA tests that detect the presence of colon carcinoma cells.

Photo by Fred Hutch Experimental Histopathology

The U.S. Preventive Services Task Force released new colorectal cancer screening guidelines Wednesday strongly suggesting Americans just get it done — however they choose to do it.

Issued by a team of national medical experts, the updated guidelines reiterate that the tests substantially reduce death from the disease, advising adults without symptoms to start screening for colorectal cancer, or CRC, at age 50 and continue to do so until age 75. After that, the decision to screen, they said, should be based on each patient’s own personal health and screening history.

The new guidelines make it clear that the type of screening people choose (there are several) is not as important as getting checked, period. People can opt for a traditional colonoscopy (which requires a day of “prep”) or they can use a test that allows them to gather a stool sample for analysis in the privacy of their own bathroom — a move they hope will motivate more people to get tested for this very preventable, treatable and beatable cancer.

“The best screening test is the one that gets done,” the task force wrote in its final report. “Offering choice in colorectal cancer screening strategies may increase screening uptake … the goal is to maximize the total number of persons who are screened because that will have the largest effect on reducing colorectal cancer deaths.”

Screening is “substantially underused,” the task force stressed in the report. One third of eligible adults in the U.S. have never been screened, despite the fact colorectal cancer is the second leading cause of death. In 2016, these cancers will strike an estimated 134,000 people — and kill nearly 50,000. According to the American Cancer Society, half the deaths from CRCs might be easily prevented by regular screenings since doctors can then find and remove polyps before they become cancerous.

Dr. Beti Thompson, who lost her son to colorectal cancer four years ago, talks about her efforts to raise awareness about CRC screening in adults over 50.

The choice is yours

Dr. Beti Thompson, a public health researcher with Fred Hutchinson Cancer Research Center, said offering people screening choices is a smart move.

“I think it’s good because it will give more people an opportunity to do a less-invasive and less-costly test in the beginning,” she said. “And hopefully that will convince more people it’s something they should do on a regular basis.”

Thompson, who lost a son to colorectal cancer four years ago, is a staunch advocate for colorectal screening and awareness. She uses a variety of methods — including community events where people can walk through a giant, inflatable colon — to educate the public about the importance of finding and catching these cancers early.

Her research has shown that when presented with information — and less invasive options — people are much more willing to undergo testing.

“We handed out home FOBT tests [fecal occult blood tests] to individuals over 50 who walked through our giant colon,” she said. “And some 76 percent of the participants returned their home kits [for lab analysis]. That’s a very high percentage. It’s one thing to think about going to have a colonoscopy and it’s another thing to think about doing a FIT [fecal immunochemical test] or FOBT kit at home. The prep [for a colonoscopy, etc.] is something that keeps a lot of people away from getting screened.”

Colonoscopy and other scope tests require a liquid laxative to completely clean out the colon before the test is performed.

The new guidelines offer seven different options for CRC screening, including colonoscopy, flexible sigmoidoscopy, CT colonography (all of which require prep, although the CT colonography test is said to be less invasive) as well as the fecal occult blood test, the fecal immunochemical test (or FIT), and the multi-targeted stool DNA test. A final option combines a flexible sigmoidoscopy with FIT. 

With the FOBT, the FIT and the FIT-DNA tests, people gather stool samples at home and send them in for analysis. The other tests, which use a tiny camera or tube inserted into the rectum, require a visit to a doctor’s office — or in the case of colonoscopy, a medical center or clinic.  Home tests need to be done more frequently than those performed by a medical professional.

(See additional details on the various tests below.)

Changing test landscape

Thompson said each of the tests has its own pros and cons. Home kits don’t require the prep and allow for more privacy. But colonoscopies are more “one and done.”

“You don’t have to do it for [another] 10 years unless they find something,” she said. “If you find something abnormal in one of the home-testing kits, then you still have to go have a colonoscopy to check out whether you have polyps or an active cancer. But if the home kit turns out negative, you don’t have to go through that screening as long as you continue with the home kits.”

So far, the only FIT-DNA test available is Cologuard, approved by the FDA in August 2014. On the plus side, the task force said that test’s sensitivity and specificity in detecting colorectal cancer was 92 percent and 84 percent, respectively. On the minus side, it might produce more false-positive results, which would require more diagnostic colonoscopies, and it might spur an overabundance of surveillance due to the genetic component of the test.

“The FIT test is a very good test,” said Thompson. “But the FIT-DNA also collects information on whether you have any of the genetic markers that have been associated with colorectal cancer, like Lynch syndrome. The FIT-DNA, I’m assuming, is going to be much more expensive.”

According to the Cologuard website, the maximum out-of-pocket cost for their test is $649, “depending on the covered benefits of your specific insurance plan.” Medicare does cover Cologuard’s FIT-DNA test but only for eligible patients.

Thompson stressed people should discuss the various test options — and their family history —with their doctors. Those with a family history of colorectal cancer or other risk factors usually need to be screened on a different schedule than those who have no risk factors.

Dr. Ruth Etzioni

Dr. Ruth Etzioni

Photo by Robert Hood / Fred Hutch News Service

Life-saving tests

Dr. Ruth Etzioni, a Fred Hutch public health researcher who’s served on similar screening guidelines committees, said there’s no question colorectal screening saves lives.  And unlike other screening tests, such as mammograms for breast cancer and PSA tests for prostate cancer, colorectal screening is less ambiguous with regard to the potential harms and benefits.

“In both colorectal and cervical [cancers] there’s a precancerous phase and if you catch the lesion in that phase, you can eliminate it,” she said. “It’s primary prevention. You’re getting a bigger bang for your screening buck.  And there’s not as much controversy about harms versus benefits.”

The problem is people don’t want to do it.

“People have an aversion to stool,” she said. “But they need to understand they need to be screened. If you compare any of these [types of tests] with no screening, there are clearly benefits.”

Since the home tests are so easy to use, Etzioni said she may even try one.

“I haven’t done it yet but I’m considering it,” she said. “I’m not due for a colonoscopy for a few years but I do have a family history. So in the interim I might use one of the home tests.”

The bottom line:

A number of CRC screening tests are available, each with its own advantages and disadvantages. Less invasive tests usually need to be performed more often, such as once a year. Others, like colonoscopy, need to be done every 10 years. Talk with your doctor to figure out which test is right for you.

Stool-based tests include:

  • FOBT or fecal occult blood test (performed annually). In this test, which checks for blood in the stool, people gather samples from two or three consecutive bowel movements and pass them onto a doctor’s office or lab for testing. There is no prep, but people may need to avoid certain foods or medications beforehand. If blood is found, a colonoscopy will be needed to determine if it’s from cancer or some other cause. 
  • FIT or fecal immunochemical test (performed annually). Similar to the FOBT, this test checks for blood in the stool in a different way. Multiple stool samples are required, but there are no drug or dietary restrictions. As with the FOBT, if blood is found, a colonoscopy will be required to determine the source.
  • FIT-DNA or multi-targeted stool DNA test (performed every one to three years). This test checks for blood in the stool as well as DNA mutations that might drive colorectal cancer. Available only by prescription, this kit comes via mail with tools to help people gather an entire stool, which is then mailed off for testing. If the test finds blood or DNA mutations, a colonoscopy will be needed.

“Direct visualization” tests take pictures of all or part of the colon, using a tiny camera or X-rays. They include:

  • Colonoscopy (performed every 10 years).  In this 30-minute test, a doctor examines the entire colon and rectum using a tiny camera. Patients need to prep in advance by drinking a large amount of liquid laxative. A special diet may be required beforehand, as well. A sedative is used during the test, which is usually performed in a hospital outpatient setting or clinic. Unlike other tests, doctors can also remove or biopsy suspicious-looking polyps.
  • CT colonography (performed every five years). This test uses a CT or CAT scan (i.e. multiple X-rays) of the colon and rectum to look for polyps or cancer. It’s done quickly (it only takes 10 minutes or so), doesn’t require sedation and is somewhat less invasive, but prep is still required. People may also need to drink a “contrast” solution beforehand. If suspicious polyps or other areas are found, a colonoscopy will most likely still need to be used.
  • Flex sig or flexible sigmoidoscopy (performed every five years). This test allows a doctor to examine the rectum and part of the colon using a flexible lighted tube with a tiny camera on the end. It requires a prep of some sort so the colon is cleaned out and may also require a special diet beforehand. The test takes about 10 to 20 minutes and doesn’t necessarily require sedation (although it’s an option if you prefer). If a small polyp is found, the doctor can remove it. If it’s found to be cancerous (or pre-cancerous), a colonoscopy will need to be done to check the rest of the colon.

Combination tests:

  • Flex sig with FIT (performed every 10 years). A combination of the above test with a home FIT test that requires gathering samples from multiple stools. Again, if blood or suspicious polyps are found, a follow-up colonoscopy will be required.

Diane Mapes is a staff writer at Fred Hutchinson Cancer Research Center. She has written extensively about health issues for NBC News, TODAY, CNN, MSN, Seattle Magazine and other publications. A breast cancer survivor, she also writes the breast cancer blog doublewhammied.com. Follow her on Twitter @double_whammied. Email her at dmapes@fredhutch.org.

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