What are the major limitations of tumor markers?

• A. Sensitivity and specificity
• B. Cost
• C. Turnaround time
• D. Imprecision

Answer: (A)

The fundamental limitation of tumor markers lies in their imperfect ability to distinguish cancer from non-cancer, which comes down to sensitivity and specificity. If sensitivity is not high enough, some cancers won't elevate the marker at all, leading to false negatives. If specificity is not high enough, benign conditions or other non-malignant processes can raise the marker, causing false positives. Because of this, a marker cannot by itself confirm a cancer diagnosis or reliably screen the general population; it’s most useful for monitoring disease activity, guiding treatment decisions, and assessing response rather than as a standalone diagnostic test. Costs, turnaround time, and analytical imprecision are important practical considerations, but they do not override the intrinsic issue that no marker perfectly detects cancer across all patients.