Are immunochemical fecal occult blood tests (FOBTs) sensitive and specific enough to be used for colorectal cancer screening?
Immunochemical FOBTs, such as OC-Micro, OC-Sensor, or OC-Light, are moderately sensitive (73% to 89%) and highly specific (92% to 95%) for identifying colorectal cancer. In comparison, Hemoccult Sensa has a lower sensitivity (64% to 80%) and specificity (87% to 90%). Immunochemical FOBTs also have the advantage of requiring only one sample. (Level of Evidence = 1c)
These researchers searched five databases and the reference lists of included studies, finding 19 eligible studies that evaluated the diagnostic accuracy of immunochemical FOBTs. Two authors used the STARD (Standards for Reporting of Diagnostic Accuracy) and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocols and independently determined study eligibility, extracted the data, and evaluated study quality. They included cohort studies and randomized studies that used colonoscopy or longitudinal follow-up as the diagnostic standard and only included studies published in English. They excluded studies or results that evaluated only the detection of adenomas.
Limiting analysis to only currently available immunochemical FOBTs found a sensitivity of 82% (95% confidence interval, 73% to 89%) and a specificity of 94% (95% confidence interval, 92% to 95%). These numbers translate into a positive likelihood ratio of 13.10 and a negative likelihood ratio of 0.19. There was no difference in performance among different commercial products, and multiple sampling was no more accurate than a single sample. Heterogeneity among the studies was acceptable when removing products that are not commercially available. There was some evidence of publication bias. There are no head-to-head studies comparing one type of test with another, and no research evaluating the effectiveness of immunochemical FOBT testing on cancer-related mortality or all-cause mortality.
Study design: Meta-analysis (other)
Funding source: Government
Setting: Various (meta-analysis)
Reference: LeeJKLilesEGBentSLevinTRCorleyDAAccuracy of fecal immunochemical tests for colorectal cancer: systematic review and meta-analysis. Ann Intern Med.2014; 160( 3): 171– 181.