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Annual FITs Effective for Colorectal Cancer Screening
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Annual home fecal immunochemical tests demonstrated high sensitivity and specificity for identifying colorectal cancer, according to research published in Annals of Internal Medicine.
“Colorectal cancer (CRC) is a leading cause of death among digestive diseases and the second leading cause of cancer-related death in the United States,” Thomas F. Imperiale, MD, professor of medicine at Indiana University School of Medicine, and colleagues wrote. “Despite the effectiveness and cost-effectiveness of screening, only 60% to 65% of the eligible population is current with screening, a rate that has fallen short of the goal of 80% by 2018.”
“This reflects concerns over the best test and strategy for screening,” they added. “Colonoscopy is the most frequently used screening test in the United States, but several other countries use annual or biennial stool blood tests or a combination of stool testing and lower endoscopy.”
Imperiale and colleagues conducted a systematic review and meta-analysis to summarize fecal immunochemical test (FIT) performance characteristics for CRC and advanced adenomas and identify contributing factors of these characteristics. The researchers looked at 31 studies with low to moderate risk for bias that assessed FIT sensitivity and specificity for colonoscopic findings in a total of 120,255 asymptomatic average-risk adults.
The researchers found that performance characteristics of FIT were dependent upon the threshold for a positive result.
For CRC, sensitivity was 0.91 (95% CI, 0.84-0.95) and the negative likelihood ratio was 0.1 (95% CI, 0.06-0.19) at a threshold of 10 g/g. When the threshold was greater than 20 g/g, the specificity was 0.95 (95% CI, 0.94-0.96) and the positive likelihood ratio was 15.49 (95% CI, 9.82-22.39).
For advanced adenomas, a threshold of 10 g/g resulted in a sensitivity of 0.4 (95% CI, 0.33-0.47) and a negative likelihood ratio of 0.67 (95% CI, 0.57-0.78). When the threshold was greater than 20 g/g, the specificity was 0.95 (95% CI, 0.94-0.96) and the positive likelihood ratio was 5.86 (95% CI, 3.77-8.97).
Heterogeneity varied across studies depending on the threshold. For one qualitative FIT for CRC, the sensitivity was 0.9 and the specificity was 0.91 at a threshold of 10 g/g, while the positive likelihood ratio was 10.13 and the negative likelihood ratio was 0.11.
Results were inconclusive when comparing three FITs at three thresholds.
“This systematic review provides new information about FIT performance characteristics for CRC and advanced adenomas as a function of test threshold,” Imperiale and colleagues concluded. “The findings suggest that FITs may be highly sensitive for CRC in a single application, though at the expense of a high false-positive rate. At high specificity, FITs are moderately sensitive for CRC.
“Although FITs are much less sensitive for advanced adenomas, the natural history of these lesions suggests annual transition rates to CRC of 3% to 6%, implying an opportunity for detection with programmatic screening,” they added. “Health care systems need to consider the quantity and quality of data for a specific FIT, comparability of the population to the study populations for that particular FIT, and the clinical and economic effects of different test thresholds on colonoscopy and systems resources to optimize FITs for early detection and prevention of CRC.”
In the accompanying editorial, James Allison, MD, from the University of California, San Francisco, and Kaiser Permanente Northern California Division of Research, wrote that many PCPs and their patients may not be aware that FITs are noninvasive, easy to prepare, inexpensive and similarly effective to colonoscopies for screening for CRC.
Physicians recognizing the advantages of FITs as screening tests for CRC and supporting raising screening rates is critical, he wrote.
“If we hope to achieve national goals for CRC screening, we must learn as much as we can about the screening tests and advocate for funding of comparative studies of available tests and insurance coverage not only for screening colonoscopies but for those done after a positive FIT result,” he wrote. – by Alaina Tedesco
Disclosures: All authors report no relevant financial disclosures.
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