Lead time bias in cancer screening programs causes:
- A Overestimation of survival time after diagnosis due to earlier detection without actual mortality benefit ✓
- B Preferential detection of slow-growing tumors, giving falsely better prognosis
- C More aggressive tumors being missed by screening, giving falsely better apparent survival
- D Length of time between detection and death remaining unchanged despite screening
Correct answer: A. Overestimation of survival time after diagnosis due to earlier detection without actual mortality benefit
Explanation
Lead time is the period between screen-detected diagnosis and the time the disease would have been diagnosed clinically in the absence of screening. Lead time bias occurs when this earlier diagnosis is mistakenly interpreted as prolonged survival — the patient appears to 'live longer' with their cancer, but the actual date of death may be unchanged. This inflates survival statistics without confirming true mortality benefit. Option B describes length-biased sampling (length time bias), where screening preferentially detects indolent/slow-growing tumors.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.