WASHINGTON – Ron Cox's doctor recommended a check for colon cancer when he turned 50. He did not get one. Nor did he get one when he turned 51, 52 or 53.

Maybe when I'm 60, Cox told himself.

Like many people, the uncomfortable preparation and intrusive nature of a traditional colonoscopy put him off.

Cox isn't sure he would ever have gotten checked for colon cancer if doctors at the Mayo Clinic had not developed a painless, accurate, noninvasive screening. He took Mayo's Cologuard stool DNA test in the privacy of his bathroom and sent it to a lab for analysis.

"There's no comparison in the real cost of seeing a doctor and pooping in a box," said Cox, an associate dean at Iowa State University's College of Engineering.

Cases like Cox's are one reason Mayo is challenging the U.S. Preventive Services Task Force for not choosing Cologuard as a diagnostic of choice for colon cancer and precancerous polyps.

The other reason is the ability of the Mayo test to screen for colon cancer in communities without access to traditional medical facilities.

The Rochester-based medical institution definitely has a financial interest in getting its new portable test in play for millions of Americans recommended for colon cancer screenings each year. But there's another reason for the urgency. Colorectal cancer is the third-leading cause of cancer deaths in the United States and is expected to take 49,700 lives in 2015.

The Mayo test "could save tens of thousands of lives in the next few years," said Mayo gastroenterologist David Ahlquist, who worked two decades to help develop it.

"This is a big opportunity."

At stake is the willingness of health insurance companies to pay for the stool DNA test. Without a Preventive Services Task Force endorsement, Mayo officials say, fewer than half of private insurance companies will reimburse for Cologuard. Also critical for Mayo is getting the cancer screening technique covered under the Affordable Care Act.

Tested in Alaska

Ahlquist tested what is known as a "multitargeted stool DNA" test among Alaska Natives who have little access to regular medical facilities, but twice the rate of colon cancer as the overall U.S. population.

That study and another in a more general group of patients showed the Mayo screening tool is as effective as traditional colonoscopy and better than two other tests recommended by the task force, Ahlquist said.

Still, the task force relegated stool DNA testing to an "alternative" status, suggesting instead that doctors and patients rely primarily on colonoscopies, sigmoidoscopies and fecal blood tests.

"Multitargeted stool DNA testing may be useful in select clinical circumstances," Dr. Albert Siu, the task force's chairman, told the Star ­Tribune in an e-mail.

"However, there is less mature evidence to support this method, resulting in greater uncertainty about its net benefit and the most appropriate situation in which to use it. At present, there is only one published study that looks at the ability of the test to accurately identify cancer, no evidence from clinical trials on how often we should repeat this test over time, and no information on the effects of the test on health outcomes."

Mayo wants the task force to elevate stool DNA testing to a "front-line" diagnostic test. In a strongly worded letter, the clinic insisted that the test provides doctors "the ability to detect and treat patients earlier than conventional screening methods."

Despite Mayo's lobbying, Siu indicated that changing the task force recommendation would be difficult.

"It is rare that new evidence between the draft and final recommendation stage emerges and meets the task force's criteria for inclusion," he said.

Ahlquist questioned how the task force could snub stool DNA testing, which is FDA and Medicare approved, in favor of less effective approaches.

"It seems illogical," Ahlquist said in an interview. "At what point does ­innovation make the cut?"

The American Cancer Society Cancer Action Network (ACSCAN) has entered the lobbying, urging the task force to include stool DNA testing among recommended tests because it performs comparably to other diagnostics that received the task force blessing.

"The creation of a new category, 'Alternative Tests,' will undoubtedly create confusion among providers, payers and the public," ACSCAN said in a letter to the task force. The cancer network said the latest incarnation of stool DNA testing has "evolved" into one with "superior performance."

Given that performance, ACSCAN called for "prompt reconsideration of the draft position" on stool DNA testing. That needs to happen, the cancer society said, if for no other reason than the fact that noninvasive DNA testing might make patients more compliant.

Mayo's Ahlquist said there is no sure figure for the number of Americans who forgo colorectal cancer screening because they lack medical access or fear traditional ­procedures.

But he placed the number in millions and perhaps tens of millions. The doctor said this was why he worked so long to develop the stool DNA test.

ACSCAN meanwhile, warned that stool DNA tests need to be acknowledged because they "may be the only test some adults will choose for colorectal cancer ­screening."

Cox can testify to that.

"I have as much trust in the test as I do in a colonoscopy," he said.

"To me, this is about quality of life, and I don't know why there is resistance."

Jim Spencer • 202-383-6123