CA-125
Pronunciation: C-A one-twenty-five
Also written as: CA-125 — Carbohydrate Antigen 125
A tumor marker blood test commonly used in ovarian cancer screening, diagnosis, and monitoring.
Full Definition
CA-125 (carbohydrate antigen 125) is a glycoprotein that serves as a tumor marker, particularly for epithelial ovarian cancer. Elevated serum CA-125 levels (>35 U/mL) are found in approximately 80% of women with advanced ovarian cancer and 50% with early-stage disease. However, CA-125 is not specific for ovarian cancer and can be elevated in benign conditions such as endometriosis, fibroids, pregnancy, and other malignancies. The marker is most useful for monitoring treatment response and detecting recurrence in patients with known ovarian cancer rather than as a primary screening tool. Serial CA-125 measurements provide more clinical value than single determinations.
Usage
Usage note: Include hyphen: 'CA-125' not 'CA125'. Units are typically expressed as U/mL.
In Context
- "Pre-operative CA-125 was markedly elevated at 450 U/mL, consistent with advanced ovarian cancer." — Laboratory report
- "Serial CA-125 monitoring showed a progressive decline following chemotherapy initiation." — Oncology follow-up note