There are now a number of ways to get screened for colorectal cancer, but not all of them are created equal, according to a new report.
The U.S. Preventive Services Task Force’s draft report on colorectal cancer detection recommends screenings beginning at age 50.
The task force found three types of tests the most useful, with two common screening methods less desirable.
One recommended approach is having a guaiac-based fecal occult blood test or a fecal immunochemical test (FIT) every year. Both look for blood in stool but in different ways.
Another is a combination of annual FIT and a flexible sigmoidoscopy every 10 years. A sigmoidoscopy is a scope test that examines the lower part of the colon and can be performed without sedation.
The third recommended strategy is a colonoscopy every 10 years. A colonoscopy looks at the entire large intestine and typically is performed with sedation.
The task force is accepting public comments on its draft recommendations until Nov. 2.
Concerns Over Two Tests
In their report, the task force said more information and study is needed on CT colonography tests before they can be endorsed as a top-tier diagnostic tool.
The report authors state that, although there is some evidence a colonography can find potential problems, there is usually the need for diagnostic follow-up.
In addition, although the radiation exposure is comparatively low during these tests, there are concerns about long-term exposure over repeated exams.
Another type of screen, known as a stool DNA test, needs more research and the task force expressed concerns about false-positive results and the need for colonoscopy follow-ups.
Nonetheless, the CT colonography and stool DNA test are still listed and may be useful in select circumstances, said Dr. Albert Siu, the task force chairman.
"The most important thing is to get people screened, one way or the other," he said.
Siu noted that, overall, clinical circumstances and patient preference will help determine the procedure used in individual cases.
"I'm not suggesting a clinician present all the choices to a patient. Depending upon their practice pattern, they'll give a patient a choice between one or two," said Siu, an internist and professor at the Icahn School of Medicine at Mount Sinai in New York.
Siu explained that each test has positives and negatives.
“Some people won't want to do preps,” he said. “Some won't want to do a stool sample at home. Some won't like the radiation exposure."
Whatever the case, he pointed out studies have shown that, given options, individuals are more likely to submit to a screening of some kind.
Colonoscopy Still the ‘Gold Standard’
Perhaps, but to Dr. Alan Venook, "nothing can replace a colonoscopy."
Venook, an oncologist, understands that the goal of the task force is to provide patients who won't undergo a colonoscopy with options.
“Nevertheless, if (a different) test isn't good enough, I'm not sure it's the answer,” he said. “The other techniques are less proven and may not be nearly or quite as good."
Instead, Venook, who is also a professor in the School of Medicine at the University of California, San Francisco, would invest time researching ways to distinguish those who need the procedure from those who don't.
Some patients need more accessible alternatives to a colonoscopy, such as tests that don’t require an extra visit to a medical facility, for example.
"My argument would be to research [the other options] and make sure we're not pretending they're as good as colonoscopies,” he said. “It's valid that [the task force] would say 'We're not getting everyone with a colonoscopy, so we should do something else.’ But let's make sure what we do works and is accessible. If not, let's not advertise it as such.”
Dr. Deborah Fisher believes the viability of alternative tests depends on a practitioner’s goals.
"I agree with the task force. There's no single, best test. It depends on how you define 'best.' If you define it by the most accurate test for finding colorectal cancer, a colonoscopy is the easy winner, the gold standard,” said Fisher, an associate professor of medicine at Duke University. “But it's also invasive and there's a risk of major complications, such as perforation and bleeding. There's even a measurable risk of death. One in 10,000 is one in 10,000.”
And colonoscopies require a degree of commitment from a patient, not to mention the ability to overcome potential accessibility issues, she added.
"It can be a real [problem] if you live in a rural area and the nearest facility's four hours away. Even if it's completely paid for, there might be out-of-pocket expenses. You miss a day of work. You need a driver," said Fisher.
For those who opt against a colonoscopy, Fisher said she'd recommend the FIT method.
"It's inexpensive, available, and insurance pays for it." Studies also have shown it increases adherence to screening, she noted.
Colorectal Cancer Common but Treatable
Colorectal cancer is the second leading cause of cancer death in the United States.
In 2015, an estimated 133,000 persons will be diagnosed with the disease and about 50,000 will die from it.
It's most frequently diagnosed among adults ages 65 to 74 years. The median age of death from colorectal cancer is 73 years.
With early detection, says medical experts, the disease is easily treatable.
Yet, about 30 percent of the U.S. population over the age of 50 has never had a colonoscopy.
"All the screening tests involve stool, so there's the 'yuck factor' of dealing with your poop," said Fisher. "With a colonoscopy you've got to prep and there's more poop. People don't get terribly excited about it."
While blood tests are easier, none is as accurate as the stool tests, said Fisher.
"A blood test might get more people excited about getting screened for colorectal cancer and eliminate the 'yuck factor,' but we're not there yet," said Fisher.