Which of the following harms is a concern in preventive screening?

• A. No risk
• B. Harms from false positives and overdiagnosis
• C. Guaranteed benefit for all individuals
• D. Immediate cure

Answer: (B)

Preventive screening isn’t risk-free; while it aims to find disease early, it can introduce harms. The most pertinent harms in screening are those from false positives and overdiagnosis. A false positive occurs when the test indicates disease when none is present, leading to anxiety and often unnecessary, potentially invasive follow-up tests or procedures with their own risks. Overdiagnosis means identifying a disease (often a slow-growing cancer) that would not have caused symptoms or shortened life, which can result in unnecessary treatment and its side effects without real benefit. The other options don’t fit the reality of screening: there is some risk with screening, benefits aren’t guaranteed for everyone, and screening does not produce an immediate cure.