Which statement best describes the fecal immunochemical test (FIT) in terms of sensitivity and specificity?

Which statement best describes the fecal immunochemical test (FIT) in terms of sensitivity and specificity?

• A. Highly specific with high sensitivity
• B. Sensitive, but not specific, leading to false positives
• C. Equally sensitive and specific
• D. Not suitable for colorectal cancer screening

Answer: (B)

Focus on how sensitivity and specificity relate to what FIT actually detects. The test looks for human hemoglobin in stool, which means it will light up when there's bleeding in the lower GI tract, including cancers and many benign conditions. Because it’s good at catching bleeding sources, FIT has high sensitivity for detecting colorectal cancer. But bleeding can originate from non-cancer causes such as hemorrhoids, diverticulosis, inflammatory diseases, or recent NSAID use, so a positive result doesn’t prove cancer and can occur with non-cancer conditions. That makes FIT not perfectly specific for cancer, even though it’s more specific than older stool tests. In practice, this combination—high sensitivity with some imperfect specificity—explains why a positive FIT indicates further evaluation (like colonoscopy) to confirm whether cancer or another pathology is present.

Focus on how sensitivity and specificity relate to what FIT actually detects. The test looks for human hemoglobin in stool, which means it will light up when there's bleeding in the lower GI tract, including cancers and many benign conditions. Because it’s good at catching bleeding sources, FIT has high sensitivity for detecting colorectal cancer. But bleeding can originate from non-cancer causes such as hemorrhoids, diverticulosis, inflammatory diseases, or recent NSAID use, so a positive result doesn’t prove cancer and can occur with non-cancer conditions. That makes FIT not perfectly specific for cancer, even though it’s more specific than older stool tests. In practice, this combination—high sensitivity with some imperfect specificity—explains why a positive FIT indicates further evaluation (like colonoscopy) to confirm whether cancer or another pathology is present.