HealthDay News — An at-home test that looks for hidden blood in the stool may be an effective way to screen for colorectal cancer, results of a meta-analysis suggest.
In a review of 19 studies, fecal immunochemical tests (FITs) caught about 79% of colon tumors and were good at ruling out the cancer, Jeffrey K. Lee, MD, of the University of California in San Francisco, and colleagues reported in Annals of Internal Medicine.
Current screening guidelines state that people at average risk of colon cancer begin annual screening via colonoscopy, sigmoidoscopy or FIT at age 50 years, but about 28% of Americans aged 50 and older have never underwent any type of screening for the disease.
Although colonoscopy is considered the gold standard for screening, more clinicians have been using FITs in recent years, because they are less invasive and easier to use.
But questions remain about the specificity of FITs — the likelihood of a positive test result when a person has colon cancer — as previous studies have reported a wide range. So Lee and colleagues conducted a systematic review and meta-analysis of 19 studies encompassing eight brands of FITs to assess the tests’ diagnostic accuracy in asymptomatic, average-risk adults.
The overall diagnostic accuracy of FITs was 95% (95% CI: 93-97%), the pooled sensitivity was 0.79 (95% CI: 0.69- 0.86), and the pooled specificity was 0.94 (95% CI: 0.92-0.95). Using a lower assay cutoff value for a positive test result, such as less than 20 µg/g, improved sensitivity to 0.89 (95% CI: 0.80 to 0.95) but decreased specificity.
“FITs are moderately sensitive, are highly specific, and have high overall diagnostic accuracy for detecting colorectal cancer. Diagnostic performance of FITs depends on the cutoff value for a positive test result,” the researchers concluded. “Health systems wishing to optimize use of a quantitative FIT should consider the tradeoff between increasing sensitivity (by lowering the cutoff threshold for a positive test) and the resulting increase in the number of positive test results, which will have a greater effect on colonoscopy resources.”
Additional studies are necessary to determine how FIT compares with colonoscopy in reducing colorectal cancer mortality.