In a randomized trial of lung cancer screening with low-dose CT, some nodules detected and treated were slow-growing lesions that would never have caused symptoms or death during the patient's natural lifespan. Treating these patients nevertheless counts them as screen-detected survivors. This distortion is called:

• A Lead time bias
• B Length time bias
• C Recall bias
• D Overdiagnosis bias ✓

Explanation

Overdiagnosis is the extreme form of length-time bias in which the detected lesion meets histological criteria for cancer but would never progress to cause clinical disease or death. These pseudo-cases inflate survival statistics without reducing mortality. Lead time bias merely shifts the date of diagnosis earlier for genuinely lethal cancers, and recall bias concerns differential accuracy of exposure memory, so neither captures non-progressive lesion detection.

Reference: Gordis Epidemiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.