, researchers report.
However, the number of people in the study who subsequently underwent timely colonoscopy after a positive blood test did not increase, signaling a continuing challenge in CRC prevention and treatment.
“The main message is that the blood test can do what it’s meant to do, which is increase screening uptake,” first author Peter Liang, MD, MPH, told this news organization. Dr. Liang is a gastroenterologist and researcher at NYU Langone Health and the VA New York Harbor Health Care System in New York.
The study was published online in Clinical Gastroenterology and Hepatology.
In the United States, the rate of use of first-line screening has for years been stuck at about 70% or lower for eligible people, Dr. Liang said. A different modality is needed to help raise the numbers.
The blood test is easy to perform and requires only a few tubes of blood, he noted. No diet restrictions, test prep, or contact with stool is necessary.
We are all searching for ways to get that first-line screening rate up from 60% to 70% to 80% to 90%, noted Folasade P. May, MD, PhD, who was not involved in the study.
“A lot of people think these blood tests are the promised land,” said Dr. May, associate professor of medicine at the University of California, Los Angeles, and director of the gastroenterology quality improvement program at UCLA Health. “We want to see that, when we offer these blood tests, the uptake is 20%-25% higher, which would get us closer to the national goal of 80% screened.”
Blood test as a second-line screening option
The study enrolled 359 veterans at a Veterans Affairs medical center. Participants were 50-75 years old and were eligible for screening but had declined a colonoscopy and a stool test within the previous 6 months.
They were randomly assigned to one of two groups. The control group received a letter and telephone outreach in which participants were again offered screening with colonoscopy or FIT only. The intervention group was additionally offered the blood test as a second-line option.
The primary outcome was completion of any screening test within 6 months. The secondary outcome was completion of a full screening strategy within 6 months, including colonoscopy for those with a positive noninvasive test result.
Of the people who had declined first-line tests and were reoffered first-line tests and the blood test, 17.1% completed screening within 6 months, compared with 9.6% of those who were only reoffered the first-line tests. The uptake of colonoscopy and FIT was similar between the two groups. The full-screening strategy was completed by 14.9% in the intervention group, compared with 9% in the control group.
At first glance, the results for uptake seem a bit disappointing, Dr. May said. However, the numbers in this study may not reflect the true potential of the blood tests – which are relatively new and have not yet been incorporated into routine care – because they had to be conducted in a separate appointment at a lab, she said.
If blood tests for CRC were part of the workflow, Dr. May explained, patients could undergo them with a routine blood draw already scheduled to check for diabetes or high cholesterol, for instance, and the numbers presumably would go up.
“I think this study underestimates the proportion of people who will participate,” she said. “We need a study that tests this strategy in a more real-world scenario.”
Nonetheless, “This is the first trial that’s looking at this question, and it’s an important question,” Dr. May added.
Dr. Liang and colleagues acknowledge that a limitation of the study is that it was performed in only one VA center among an older, predominantly male population, so it will be important to make the comparisons in more diverse study populations.