Study will compare fecal immunochemical tests with colonoscopy
A group of researchers at three sites in the United States have received a $4.5 million grant to determine the relative effectiveness of four fecal immunochemical tests for colorectal cancer screening compared with colonoscopy.
Navkiran Shokar, MD, MPH, MA, professor, vice chair for research and director for cancer prevention and control at Texas Tech University Health Sciences Center El Paso, and colleagues intend to enroll 3,600 adults aged 50 to 85 years who have been designated for a colonoscopy.
Study participants will be given four fecal immunochemical tests (FIT), and then they will undergo colonoscopy.
The 5-year study — 4 years for data collection and 1 year for analysis — will be led by Barcey Levy, MD, PhD, Iowa Academy of Family Physicians endowed chair in rural medicine and professor of family medicine at University of Iowa.
HemOnc Today spoke with Shokar about the study, the potential implications of the results, and how FIT testing may be able to increase colorectal cancer screening rates.
Question: How can FIT tests contribute to increased colorectal cancer screening?
Answer: Colorectal cancer screening is unusual because there is more than one type of test recommended for it. In addition to colonoscopy, there are stool-based tests, FIT is an example of one of those. This type of test uses antibody to detect hemoglobin. It is more accurate than its predecessor, which was a chemical-based test. But this is only one class of tests. Other tests that are recommended include sigmoidoscopy, a stool DNA test and CT colonography. In the United States, physicians tend to prefer recommending colonoscopy because it is a one-time test, and they don’t have to worry about it again for 5 or 10 years. The problem is that patients aren’t necessarily as enthusiastic about colonoscopy as some physicians are. In order to get screening rates up, we can’t keep offering colonoscopy as the only test. We need to offer the FIT test, as well. Studies indicate that, when you give patients the choice, a certain subset will prefer FIT. If we want to get population-based screening rates improved, we have got to do a better job recommending FIT. That’s where this study comes in. Although stool-based tests are cleared by the FDA, there still is not good real-world information that will allow us to compare across different tests. This study will give physicians and patients better information about test sensitivity and test characteristics in the real world.
Q: Some people prefer FIT tests to colonoscopy because of ease of use, less embarrassment, less preparation and lower costs. Could you a ddress those and other advantages of this method?
A: I agree with all of those. There is a proportion of patients who this really appeals to. In addition to that, I would add that — although prospective evidence will be coming out about using colonoscopy for screening — the level of evidence is much higher for FIT in terms of randomized controlled trials.
Q: Please talk about the most effective or least effective stool-based tests. Are there more data available for some tests than others?
A: There is a lack of information about the relative accuracy of different FIT tests among average-risk populations in real-world settings compared with colonoscopy. Comparison analyses really need to be done. That’s what we are hoping to do. We will compare four of the most commonly used tests in the United States, and we will examine how they perform in detecting large polyps and cancer. It hasn’t been done this way in this country on an average-risk population. That’s what makes our study unique. The other attractive component of our study is that we are looking at different kinds of populations. The portion of the study performed in El Paso will be done largely in Hispanic patients, which comprise 80% of our population. A group in North Carolina will include a large number of black participants. The Iowa population is largely rural. We really will be able to generalize the results because the population of our study is so diverse.
Q: Could you talk about the study protocols?
A: Patients who have been referred for a screening or surveillance colonoscopy will be approached for participation. The patients will perform the FIT tests at home, and we will compare those results with colonoscopy. We will see how well each test detects cancer, or adenomatous polyps. We hope to establish clear information on the accuracy of these tests and how they perform against each other.
Q : Could you briefly address the knowledge gap among patients about these tests. Do you hope to raise awareness?
A: Definitely. That is a major part of this. Awareness about the importance of colorectal cancer screening is slowly increasing over time, but we still haven’t gotten to the same level of awareness as we have for other screening-detectable cancers: For example, women know they need mammograms and PAP tests. We are not at that level for colorectal cancer screening. Patients are becoming more familiar with FIT tests, but they don’t realize they can do the screening. We need to let them know. We also need to let physicians know that not every patient is excited about having a colonoscopy. The benefit is that, after they do the FIT test for a few years, the idea of a colonoscopy may grow on them. What we say about colorectal cancer screening is that any screening is better than no screening. Just match it to the patient’s preference and do it. – by Rob Volansky
For more information:
Navkiran K. Shokar, MD, MPH, MA, can be reached at Texas Tech University Health Sciences Center El Paso, 9849 Kenworthy St., El Paso, TX 79924; email: firstname.lastname@example.org.
Disclosure: Shokar reports no relevant financial disclosures.