New DNA Test Could Represent a ‘Revolution’ for Colon Cancer

Colon Cancer is the second deadliest cancer for men and women in the United States, behind lung cancer. And Alaska Natives suffer from especially high rates of the disease. Now a new colon cancer screening test is in the final stages of the FDA approval process. It was developed by a Mayo Clinic doctor who visited rural Alaska and saw the problem first hand:

When Mayo Clinic Doctor David Ahlquist took a trip to the Bethel area in the mid-1990’s a startling statistic caught his attention. Alaska Natives were – and still are – twice as likely to get colon cancer and die from the disease as U.S. Whites:

“Here they had one of the world’s highest rates of colon cancer and one of the world’s poorest outcomes in terms of survival from cancer because of late diagnosis.”

The best way to prevent colon cancer is through screening, but Dr. Ahlquist realized traditional screening methods had flaws in rural Alaska. Colonoscopy equipment isn’t available in remote Native villages. And a widely used test that detects blood in stool isn’t effective because many Alaska Natives have a stomach bacteria called H. pylori that also causes bleeding.

So when he returned to the Mayo Clinic, Dr. Ahlquist began working on a new kind of test. He wanted it to be highly accurate, accessible to anyone and easy to use. The test he eventually developed can identify several altered genes that are present in colon cancer:

“It measures DNA changes that are shed from the surface of cancer or pre cancer into the stool and we can detect those changes that act as a signature as the presence of cancer or polyps. And it proves to be very accurate.”

According to two studies published this year, the DNA test finds 85 percent of colon cancers and more than 50 percent of pre-cancerous polyps. Ahlquist and the Mayo Clinic are working with a company called Exact Sciences to commercially develop the test and both will benefit financially if it comes on the market. Ahlquist says the test could represent a revolution for colon cancer screening, much like the Pap smear did for cervical cancer half a century ago:

“The Pap smear took a target, cervical cancer, which at that time, in the ’50’s was the number one cancer killer in women in the United States. Now, in those women who are screened, it’s a rare disease. It’s essentially been eradicated in women who are screened.”

Predicting the DNA test could eventually make colon cancer a rare disease may sound like a bold claim. But its one that has merit, according to Dr. Randall Burt, Director of Prevention at the Huntsman Cancer Institute in Utah:

“In the end, it could be a huge game changer.”

Burt has been watching the development of the colon cancer test over the years as an outside observer.  And he thinks it’s fair to say the DNA test could one day be compared to the pap smear- especially if it gets better at detecting pre cancerous polyps:

“Is it enough to replace colonoscopies so we only do colonscopies on people with a positive stool test? Probably not yet. But it’s getting there.”

In anticipation of FDA approval early next year, the DNA test is undergoing a trial at more than 100 sites in the US and Canada. And Burt says it’s important for the test to prove itself in that more rigorous study.

Another expert in the field agrees. Dr. William Grady is a gastroenterologist and researcher at the Fred Hutchinson Cancer Research Center in Seattle. He is working on another version of a DNA-based stool test for colon cancer detection. Grady says DNA tests are also in the works for a long list of cancers including, lung, pancreatic and brain cancer. He says the tests will transform the way cancer is diagnosed and even treated:

“It’s very exciting, I think we’re going to really see a revolution in the way we take care of patients who have cancer.”

In Alaska, there’s hope Dr. Ahlquist’s colon cancer DNA test could help make the disease less deadly. In February, The Alaska Native Tribal Health Consortium began a three year trial of the test. 100 patients have enrolled so far. Janet Kelly is Cancer Surveillance Director at ANTHC. She says the test holds a lot of promise for Alaska Natives:

“Until we can find a cure for this cancer, the best tool we have is to screen. And early detection through this test offers a lot of opportunity.”

The colon cancer screening rate for Alaska Natives in some rural areas of the state is as low as 23%. In urban areas, it’s closer to 60%. The DNA test could level the playing field, making colon cancer screening as accessible to someone in Shishmaref as it is to someone in Anchorage.

It’s expected to cost about $300, far less than the average colonoscopy in Alaska. It could be available as soon as the middle of next year.

This story is part of a reporting partnership that includes APRN, NPR and Kaiser Health News.

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Annie Feidt is the Managing Editor for Alaska's Energy Desk, a collaboration between Alaska Public Media in Anchorage, KTOO Public Media in Juneau and KUCB in Unalaska. Her reporting has taken her searching for polar bears on the Chukchi Sea ice, out to remote checkpoints on the Iditarod Trail, and up on the Eklutna Glacier with scientists studying its retreat. Her stories have been heard nationally on NPR and Marketplace.
Annie’s career in radio journalism began in 1998 at Minnesota Public Radio, where she produced the regional edition of All Things Considered. She moved to Anchorage in 2004 with her husband, intending to stay in the 49th state just a few years. She has no plans to leave anytime soon.
afeidt (at) alaskapublic (dot) org  |  907.550.8443 | About Annie

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