FIT may be useful for screening above-average-risk populations for colorectal cancer

A meta-analysis of 12 studies found that fecal immunochemical testing (FIT) may be a viable alternative screening strategy for patients at increased risk for colorectal cancer, but the authors and an accompanying editorial noted that the quality of the evidence was low.


In patients at above-average personal or familial risk, fecal immunochemical testing (FIT) has high overall diagnostic accuracy for colorectal cancer (CRC) and moderate accuracy for advanced neoplasia, a meta-analysis found.

The analysis included 12 studies with 6,204 patients. The primary outcome was the diagnostic performance of FIT for detecting colorectal cancer or advanced neoplasia. Results were published online June 19 by JAMA Internal Medicine.

The average sensitivity of FIT for colorectal cancer was 93% (95% CI, 53% to 99%), and the average specificity was 91% (95% CI, 89% to 92%), yielding a positive likelihood ratio of 10.30 (95% CI, 7.7 to 13.9) and a negative likelihood ratio of 0.08 (95% CI, 0.01 to 0.75). The average sensitivity of FIT for advanced neoplasia was 48% (95% CI, 39% to 57%), and the average specificity was 93% (95% CI, 91% to 94%), for a positive likelihood ratio of 6.55 (95% CI, 5.0 to 8.5) and a negative likelihood ratio of 0.57 (95% CI, 0.48 to 0.67).

Subgroup analyses indicated that FIT cutoff values between 15- and 25-μg/g of feces provided the best combination of sensitivity and specificity for the diagnosis of colorectal cancer (93% and 94%, respectively), the authors wrote. Quantitative and one-sample FIT showed adequate test performance, but data on other FIT brands and multiple samples were insufficient.

The authors noted that given the safety, simplicity, low cost, and minimal discomfort of FIT, it is a viable alternative screening strategy for patients at increased risk for colorectal cancer, which is especially important for those who are averse to colonoscopy.

“The latest U.S. Preventive Services Task Force recommendations for colorectal screening support that ‘the best screening test is the one that gets done,’ and that the ultimate goal of screening strategies is maximization of screening uptake to reduce CRC mortality,” they wrote.

An editorial noted that while the meta-analysis represents the best possible use of the available data, the overall quality of the evidence is so low that future studies could contradict the results.

The editorial concluded, “The absolute numbers of missed noncancerous advanced neoplasia are probably too large to justify using FIT as a triage test in people with family or personal history of CRC or adenomas, especially since these people have a higher-than-average awareness of the importance of CRC screening, as well as higher-than-average motivation and willingness to have a colonoscopy.”