The Growing Importance of CA 19-9 in the Diagnosis and Monitoring of Malignant Ovarian Tumors

Abstract

Aim: Managing ovarian tumors is a clinical challenge due to vague symptoms, especially in young patients and athletes where saving fertility and avoiding invasive protocols are vital to healthcare quality. This study evaluates the diagnostic and monitoring role of Carbohydrate Antigen 19-9 (CA 19-9) across ovarian tumor histotypes to optimize clinical decisions and patient outcomes. Materials and Methods: A comprehensive review of literature and clinical cohorts evaluating CA 19-9 expression in epithelial ovarian cancers (serous, endometrioid, clear cell, mucinous) and germ cell tumors (mature cystic teratomas) was conducted. Databases were searched for English- and Polish-language studies published up to May 2026. Diagnostic indices, including sensitivity, specificity, and multi-marker panels (CA 19-9 combined with CA 125/HE4), were extracted and synthesized using a narrative approach across core clinical domains. Results: While CA 125 is standard for serous carcinomas, it shows poor sensitivity in clear cell and mucinous histotypes. Conversely, CA 19-9 levels are significantly elevated in mucinous carcinomas (>37 U/mL) and serve as an independent postoperative prognostic marker in clear cell carcinomas when CA 125 is normal. In endometrioid carcinomas, combining CA 19-9 and CA 125 yields a robust specificity of up to 90%. Furthermore, isolated CA 19-9 elevation in mature cystic teratomas strongly correlates with increased tumor size and thinning cyst walls, serving as a vital indicator to estimate acute adnexal torsion risks during physical strain. Conclusions: Integrating CA 19-9 into gynecological panels improves pre-operative differential diagnosis, reduces false-positive rates in active populations, and provides vital risk stratification for ovarian torsion. This multi-marker approach enhances healthcare quality and diagnostic safety in sports medicine and gynecological oncology.