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Annual FIT associated with high sensitivity, adherence to follow-up screens
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Annual fecal immunochemical testing appeared highly sensitive for colorectal cancer detection, according to results of a retrospective longitudinal study.
Because there also appeared to be high adherence to annual follow-up screening, the researchers concluded annual fecal immunochemical test (FIT) screening is a feasible and effective population-level colorectal cancer screening modality.
The U.S. Preventive Services Task Force recommends annual guaiac-based fecal occult blood tests (FOBTs) as an option for average-risk adults aged 50 to 75 years.
FIT is another noninvasive screening modality that can be delivered by mail without the requirement of dietary or medication restrictions, which could lead to greater compliance rates, according to researchers. FIT has also shown higher detection rates for colorectal cancer and advanced adenomas than FOBTs, but data after several rounds of annual FIT screening have been limited.
Douglas A. Corley
“FIT is simple to do at home but, to be most effective, needs to be done every year,” Douglas A. Corley, MD, PhD, MPH, research scientist at the Kaiser Permanente Northern California Division of Research and clinical professor of medicine at University of California, San Francisco, told HemOnc Today. “This has the advantage of potentially picking up cancers that grow between [colonoscopy] tests. There are few studies that have looked at how well FIT picks up cancers when used year after year.
“If a test picks up most cancers, it is said to be very ‘sensitive’ for picking up cancer,” Corley added. “Most studies only looked at 1 or 2 years of use for how well FIT detected cancers.”
Thus, Corley and colleagues sought to assess FIT performance characteristics over four rounds of annual screening.
The investigators followed 323,439 individuals aged 50 to 70 years at the time they were mailed a FIT in 2007 or 2008. Of those who remained eligible, most (range, 75.3%-86.1%) participated in the subsequent rounds of screening.
Across all screening rounds, 63.8% of distributed tests were completed within 1 year of mailing. Researchers noted participation was highest in patients aged older vs. younger than 65 years (77.5% vs. 60.3%.
After a median follow-up of 4 years, 32% of those who participated in round 1 of the study crossed over to endoscopy during the four screening rounds, 7% of which were due to a positive FIT result.
Five percent of results were positive in the first round of testing, and positivity rates declined thereafter (range, 3.7%-4.3%). Overall, 78.4% of participants with positive FIT underwent follow-up colonoscopy within 1 year.
Sensitivity for colorectal cancer was highest during the initial round of testing (84.5%) and stabilized in subsequent rounds (75.4% in round 2, 73.4% in round 3 and 78% in round 4).
The positive predictive values also were highest in round 1 (3.4% for colorectal cancer, 51.5% for adenoma) and stabilized thereafter (for colorectal cancer, 2.1% in round 2; 2.3% in round 3; 2.1% in round 4; for adenoma, 47.4% in round 2; 48.5% in round 3; 47.9% in round 4).
“There are a couple different effective tests for colorectal cancer screening, including colonoscopy and FIT,” Corley said. “They have different strengths and weaknesses. This study provides additional support that FIT can be an important tool for getting more people screened in a way that is both sensitive to picking up cancers and making it easier for people to comply.” – by Anthony SanFilippo
For more information:
Douglas A. Corley, MD, PhD, MPH, can be reached at douglas.corley@kp.org.
Disclosure: The study was funded by a grant from the NCI. One researcher reports a consultant/advisory role with Exact Sciences.
Perspective
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Donald S. David, MD, FACG
Fecal immunochemical testing (FIT) testing represents an effective, noninvasive method for screening populations for colorectal cancer.
It is endorsed by all of the national preventative health guidelines and, when performed annually, it provides an effective screening program to detect colon cancer at an early stage. It is not able to effectively detect polyps; however, it is unclear if this is important.
When properly performed, FIT will detect approximately 70% of colon cancers. It has the benefit of being noninvasive and very inexpensive. However, FIT only works well when performed religiously on an annual basis, and only organized managed care groups appear to be capable of administering a program that ensures that all patients receive this test annually. If it is positive, a full colonoscopy will be required.
FIT testing is more accurate than older “guaiac”-based stool testing — which can be positive with red meat consumption — but not as accurate as new stool DNA testing (Cologuard, Exact Sciences), which will pick up 92% of cases of colon cancer in a large national trial.
Cologuard is currently recommended to be done every 3 years and is more expensive than FIT testing, but may be more sensitive.
Colonoscopy remains the gold standard for colon cancer and polyp detection and removal, and offers the advantage of being able to remove precancerous lesions (polyps) at the time of the exam. It is more expensive and requires a bowel preparation and sedation. If negative, another exam is typically not required for 10 years, and FIT testing is not recommended in the intervening years.
FIT testing represents a reasonable, accurate and affordable option for colorectal cancer screening, and has been effectively used for screening by large managed care organizations with a strong primary care infrastructure (such as Kaiser Permanente). It remains to be determined if less well organized, smaller care delivery systems can use FIT effectively for cancer prevention, as it is difficult to get patients and providers to adhere to a strict yearly testing schedule.
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