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Fecal immunochemical tests detected most colorectal cancers
Fecal immunochemical tests demonstrated high overall diagnostic accuracy for detection of colorectal cancers in asymptomatic, average-risk adults, according to results of a systematic review and meta-analysis.
Results showed fecal immunochemical tests (FIT) detected 79% of colorectal cancers with one round of testing. FIT also correctly identified about 94% of patients who did not have colon or rectum cancers.
“We know the FIT is easy to use, and now we also know that it is a great tool for assessing which patients have cancer and which patients don't,” Beth Liles, MD, clinical investigator at the Kaiser Permanente Center for Health Research, said in a press release.
Prior investigations into the diagnostic accuracy of FIT yielded reported sensitivities ranging from 25% to 100%, according to background information provided by researchers. The variation has created confusion among health care providers about how to best incorporate FIT into colorectal cancer screening, the optimal number of stool samples needed for testing, the ideal cutoff value for a positive test result, and whether one type of FIT is more accurate than others.
In the current study, researchers reviewed online databases to identify 19 studies that evaluated the diagnostic accuracy of FIT for colorectal cancer in asymptomatic, average-risk adults. All studies were conducted between 1996 and 2013.
Researchers calculated an overall pooled sensitivity of 0.79 (95% CI, 0.69-0.86); a specificity of 0.94 (95% CI, 0.92-0.95), a positive likelihood ratio of 13.10 (95% CI, 10.49-16.35); and a negative likelihood ratio of 0.23 (95% CI, 0.15-0.33).
They determined the overall diagnostic accuracy of FIT was 95% (95% CI, 93-97).
Researchers reported considerable heterogeneity between studies with regard to both the pooled sensitivity and specificity estimates. When they stratified by cutoff value for a positive test results or removed discontinued FIT brands from the analysis, sensitivity estimates were heterogeneous.
Lower assay cutoff values for a positive test was associated with improved sensitivity for colorectal cancer but a corresponding reduction in specificity. Researchers determined a single-sample test yielded similar sensitivity and specificity as a multiple-sample test.
Also, no FIT brand performed markedly better than any other.
Researchers acknowledged the study had several limitations, including the heterogeneity observed in most analyses; the potential for detection, verification and spectrum biases of the original studies; an inability to determine sensitivity and specificity of FIT for proximal vs. distal colorectal cancer, and the fact that a lack of data prevented complete subgroup analysis by FIT brand.
However, considering one in three adults is not adequately screened for colorectal cancer, the results suggest FIT can be a valuable diagnostic tool, researchers said.
“FIT is simple, can be done at home and can save lives,” study author Jeffrey Lee, MD, MAS, a postdoctoral researcher at Kaiser Permanente and the University of California, said in the press release. “The American Cancer Society and other professional organizations have recommended [the test] as a screening tool for colorectal cancer since 2008, but there are still many people who don't know about it.”
Disclosure: The researchers report no relevant financial disclosures.