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Lead-time bias — USMLE Step 3 MCQ

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ModeratePreventive Medicine, Epidemiology, BiostatisticsLead-time biasUSMLE Step 3

A hospital advertises that patients whose lung cancers are detected by screening live longer after diagnosis than those diagnosed after symptoms. Population lung cancer mortality has not changed. Which of the following is the most likely explanation for this patient's findings?

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Correct answer: E — Earlier diagnosis without delayed death can increase measured survival time

Lead-time bias makes survival after diagnosis appear longer without changing time of death.

Reference: USPSTF lung cancer screening, https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/lung-cancer-screening