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UK Pilot Study Aims to Validate Rule-Out Test for Colonoscopies


NEW YORK (360Dx) – UK clinicians last week began recruiting for a clinical study to validate a rule-out test for colorectal cancer that they hope will reduce the number of unnecessary colonoscopies.

By reducing the number of people doing unneeded, invasive procedures, the test could enable a greater focus of healthcare resources on patients who are at high risk for colorectal cancer, according to the clinicians leading the project.

It could also lead to more people doing colorectal, or bowel, cancer tests because it's so easy to use, said Edward Seward, a consultant gastroenterologist at University College London Hospitals NHS Foundation Trust, which consists of several London-based hospitals participating in the pilot project.

The quantitative fecal immunochemical test, qFIT, uses latex agglutination immunoturbidimetry, a process that detects hemoglobin antibodies, and it is specific for the presence of human hemoglobin.

It has already undergone clinical evaluation at Ninewells Hospital & Medical School, Dundee, Scotland where researchers looked at the negative predictive value of qFIT in a population of people suspected of having colorectal cancer. The researchers found that when "the test was negative for the presence of blood, it was 100 percent predictive for the absence of bowel cancer," Seward said.

The Dundee researchers concluded that in a primary care setting, undetectable fecal hemoglobin "is a good ‘rule-out’ test for significant bowel disease and could guide who requires investigation."

Colonoscopy is routinely used for diagnosing potentially curable bowel cancer, but too many patients come to hospitals "to have what turns out to be an unnecessary procedure," Seward said, adding that, "There are plenty of noncancer related causes of lower gastrointestinal symptoms, and that's the problem we have with bowel cancer today."

Patients can present with several symptoms indicative of colorectal, or bowel, cancer, including rectal bleeding, anemia, diarrhea, abdominal pain, weight loss, and altered bowel habits. Patients with anemia or a mass require a colonoscopy irrespective of fecal test results. However, "if we have a test that screens out patients who don't need colonoscopies, and lets us focus on the higher-risk population, that's a better use of resources all around," Seward said.

The UCLH team leading the pilot study was particularly interested in a statistic relating to the number of tests in the Dundee study that turned out to be negative. They found that 40 percent of the tests on patients suspected of having colorectal cancer were negative. "What this means is that if we can reproduce that data, we are going to be able to do 40 percent fewer colonoscopies in this population," Seward said, adding that "it not only has massive implications in terms of concentrating our resources on a higher-risk population," but it's also important for patients, because many of them would then avoid having to endure an unnecessary invasive procedure.

Michael Machesney, pilot lead and a consultant colorectal surgeon, said in a statement that the "vast majority of colorectal cancers are diagnosed at a late stage, which is why it is the second-biggest cancer killer."

Accurately ruling out colorectal cancer for patients with lower abdominal symptoms has the potential to temper an increasing need for colonoscopy resources and transform the way that colorectal cancer is diagnosed, he said.

In 2016, UK specialists evaluated more than 260,000 patients with lower abdominal symptoms after a general practitioner referred them due to suspected colorectal cancer. Most of these patients were referred for a colonoscopy, but only about 4 percent of them had cancer, according to UCLH, which added that the burden on endoscopy departments imposed by patients requiring colonoscopies is expected to increase.

In the UK, a 44 percent increase is expected in the volume of endoscopies performed in the next five years, and health systems worldwide are facing similar challenges, Seward said. A colonoscopy is an "expensive test to deliver and it requires specialized personnel, specialized equipment, and specialized rooms," he added.

The qFIT test would cost only £3 ($3.84), which is about 1 percent of the cost of doing a colonoscopy in the UK, Seward said.

Traditional fecal occult blood testing tests are available that check for blood in a stool sample, but they are nonspecific, are thrown off by parameters such as diet, and have about a 50 percent predictive value for the presence of pathology, Seward added. Conventional testing for fecal human blood frequently requires multiple tests, he said, adding, "A patient might have to do three separate tests on separate days which makes it a very unattractive, unappealing test."

The UK project also aims to measure how various factors may influence the test's uptake. The project leaders are hopeful that the simplicity of performing the test will drive its adoption. Testing involves dipping a wand in a stool sample, inserting the wand in a cartridge, and mailing the kit to a laboratory.

Bowel cancer screening programs in the UK using stool tests have shown that the relative uptake of the test varies with patient factors, such as your postal code, relative wealth, and how you're approached to take the test, Seward said.  

"We are looking at whether we can get higher take-up when the test is requested by the primary care physician or the hospital," he added.  

UCLH has rolled out the pilot project to patients in more than 33 general practitioner practices and six hospitals within the English national health system. Patients who have been urgently referred for lower abdominal examinations, due to suspected colorectal cancer, take the qFIT test at home and send it out for testing.

To validate the test results, clinicians are comparing its results with colonoscopy outcomes. The pilot project team expects to gather results from a minimum of 2,000 patients over six months. Because of the high rate of referrals for colonoscopies, collecting the requisite number of participants should be easy, Seward said.

“If successful, the results of the pilot study could effect change across the whole of the NHS and change the way that colorectal cancer is diagnosed in England," Celia Ingham Clark, medical director for clinical effectiveness at NHS England, said in a statement.

By validating the test, the pilot study would also demonstrate its potential for adoption in multiple regions, Seward said.

"It's applicable all over. I am sure that not everyone in the US wants to go straight to a colonoscopy," he said, adding that, "If patients attend a primary care physician with bleeding and are looking for reassurance that they don't have cancer, and they find out that a test is available that can quickly tell them that they could be 100 percent sure that there's no cancer, will they go for that? Absolutely."