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The Best Colon Cancer Screening Test Is the One That Gets Done

Data presented at Digestive Disease Week 2019 suggests that more people are willing to take a blood test than a stool test to screen for colorectal cancer.

The University of Miami Mitchell Wolfson Sr. Department of Community Service in Florida hosted free health fairs between April 2017 and April 2018. Attendees who were eligible for screening and at average risk for CRC were offered a stool-based fecal immunohistochemical test (FIT), and those who declined FIT were then offered the Epi proColon blood test, which FDA approved in 2016. In prior years, these health fairs only offered FIT.

Graphic By Amanda Pedersen based on data presented at DDW 2019

Here's the bottom line: Colonoscopy continues to be the most effective screening method for colorectal cancer (CRC), but too many adults who should be screened refuse to have it done as a primary screening method.

So while the headline of this article has almost become a cliche in the world of CRC screening, perhaps it's a cliche worth embracing. A poster presentation at Digestive Disease Week 2019 in San Diego, CA did a simple yet effective job of underscoring this point.

The University of Miami Mitchell Wolfson Sr. Department of Community Service in Florida hosted free health fairs between April 2017 and April 2018. Attendees who were eligible for screening and at average risk for CRC were offered a stool-based fecal immunohistochemical test (FIT), and those who declined FIT were then offered the Epi proColon blood test, which FDA approved in 2016. Blood samples were drawn from participants who accepted Epi proColon and sent for analysis. Participants with positive Epi proColon results were contacted by student navigators to try to facilitate a colonoscopy.

Of 1,241 health fair attendees, 249 were eligible to participate in CRC screening. Of those participants, 233 (93.6%) elected to undergo Epi proColon screening. Only 16 (6.4%) of eligible participants elected to receive a take-home FIT, of which only one was returned for processing. The researchers also looked at the number of screenings from health fairs held in the prior year, which only offered FIT, and found that only 52 of 414 (12.5%) accepted FITs were processed. 

The authors conclude that the availability of the Epi proColon blood test resulted in a marked increase in screening uptake compared with FIT in medically underserved patients. The Epi pro Colon test, developed by Berlin, Germany-based Epigenomics, is indicated for the screening of adults ages 50 years or older who have an average risk for CRC and who have been offered and have a history of non-compliance with other CRC screening methods. The blood-based test leverages Epigenomics' DNA methylation biomarker technology.

"Today, we do have other tests that are available for colorectal cancer screening, and they all work," said Epigenomics CEO Greg Hamilton. "The challenge we have is that the [other] available methods are either a colonoscopy or a stool-based test, so what happens is a third of the market goes unscreened."

That means more than 30 million people that should be screened for CRC don't get screened, Hamilton said. He also cited a paper Kaiser published in 2018 that showed 70% of the deaths from colon cancer come from the unscreened market. 

"So our test is really designed for the unscreened market," Hamilton told MD+DI. "A different sample type allows people to have a different experience with the test. That's just the reality where we're at. People either refuse to get a colonoscopy or they refuse to do a stool test. Now the physician and the patient have a different option."

Another challenge with the other available screening methods is they require the patient to take action outside of the primary physician's office, whereas chances are if you're at the doctor's office for an annual physical you're going to get blood drawn anyway. With the Epi proColon test, it's just one more tube of blood on the same blood draw, Hamilton said.

"The only bad option is not getting screened," he said.

But the key word here is screened, not diagnosed. Colonoscopy is still the only procedure that can actually diagnose cancer because a CRC diagnosis requires a biopsy. All of the non-invasive CRC tests currently on the market are designed to be a first line screening tool. If that turns up positive, then the patient is referred for a colonoscopy.

Of course, patients can still opt for cutting out the screening step and going straight to the colonoscopy if they so choose.

"It's a great test and if people want to do that go for it, go get a colonoscopy," Hamilton said. "But we know that a lot of people don't so the blood test is another option."

Soon patients may have another choice, however. South San Francisco, CA-based Freenome recently initiated a clinical study to evaluate its artificial intelligence-based blood test in an effort to improve colorectal cancer screening. The AI-EMERGE study aims to collect samples from up to 3,000 people in the United States and Canada. Freenome CEO Gabe Otte said the infusion of AI is a natural step in the evolution of diagnostics that should have taken place years ago.

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