What are the limitations of CA-125 as a screening test for ovarian cancer?

• A. CA-125 is elevated only in ovarian cancer and never in benign conditions.
• B. CA-125 is highly specific for early ovarian cancer and should be used as a standalone screen.
• C. CA-125 is elevated in many benign conditions and is not sensitive for early-stage disease; not a stand-alone diagnostic test and is used mainly for monitoring.
• D. CA-125 can diagnose ovarian cancer in the absence of imaging.

Answer: (C)

CA-125 has limited usefulness as a screening test because it isn’t specific to ovarian cancer and isn’t reliably elevated in early disease. It can be raised in many benign conditions such as endometriosis, fibroids, pelvic inflammatory disease, liver disease, and even during menstruation, which leads to many false positives if used for screening. At the same time, many women with early ovarian cancer do not have a raised CA-125, so the marker misses cases when cancer is most curable. For these reasons, CA-125 is not used as a stand-alone diagnostic or screening test; it is mainly valuable for monitoring treatment response and detecting recurrence in patients with known ovarian cancer, often alongside imaging.