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Number needed to treat — USMLE Step 2 CK MCQ

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EasyPreventive Medicine & BiostatisticsNumber needed to treatUSMLE Step 2 CK

A 61-year-old asymptomatic man at average colorectal-cancer risk completes an annual fecal immunochemical test, which is positive. He has never undergone colonoscopy, takes no anticoagulant, and is healthy enough for diagnostic evaluation and treatment. Which next step is most appropriate?

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Correct answer: E — Arrange diagnostic colonoscopy to evaluate the positive screening test

A positive fecal immunochemical test is an abnormal screening result that must be followed by diagnostic colonoscopy. Colonoscopy identifies the bleeding source and permits biopsy or removal of neoplastic lesions; without this follow-up, the stool-based screening program does not confer its intended benefit. Repeating FIT is not a way to cancel a prior positive result because bleeding from advanced adenomas or cancers can be intermittent. Returning to annual stool testing or waiting for symptoms risks delayed diagnosis. Serum carcinoembryonic antigen is neither a screening test nor a diagnostic substitute for colonoscopy; it is used selectively after a cancer diagnosis for prognosis and surveillance. This patient is fit for evaluation and has no stated contraindication. If colonoscopy is incomplete or contraindicated, alternative diagnostic planning is individualized, but routine CT colonography does not remove the need to evaluate or remove lesions found after a positive FIT.

Reference: U.S. Preventive Services Task Force. Colorectal Cancer: Screening. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening