Cancer Antigen 125
Marcadores tumoralesÚltima revisión: 7 de abril de 2026. Enfoque de fuentes: contexto estándar de interpretación de laboratorio, material médico de referencia y orientación clínica o de salud pública cuando corresponde.
¿Qué es Cancer Antigen 125?
Cancer Antigen 125 (CA-125) is a glycoprotein encoded by the MUC16 gene that is expressed on the surface of cells derived from coelomic epithelium, including the mesothelial lining of the peritoneum, pleura, and pericardium, as well as the epithelium of the fallopian tubes, endometrium, and endocervix. CA-125 is shed from cell surfaces into the bloodstream and can be measured via immunoassay. It was first identified in 1981 using monoclonal antibody OC125, which recognized an antigen consistently elevated in the serum of patients with epithelial ovarian cancer.
CA-125 is most widely used as a serum biomarker for monitoring treatment response and detecting recurrence in patients with epithelial ovarian cancer, particularly serous carcinomas. It is not recommended as a standalone screening tool for ovarian cancer in the general population because of its limited sensitivity in early-stage disease and its poor specificity—many benign conditions also elevate CA-125. However, in combination with transvaginal ultrasound, it may have a role in screening high-risk populations. Serial measurements are generally more informative than single values.
Por qué importa
CA-125 is the most established serum biomarker for epithelial ovarian cancer, used primarily to monitor treatment response and detect disease recurrence. A rising CA-125 after treatment can signal relapse months before imaging findings appear. However, CA-125 has important limitations: it is elevated in only about 80% of advanced ovarian cancers and fewer than 50% of early-stage cases. Many benign gynecological and non-gynecological conditions can raise CA-125, so results must always be interpreted in clinical context. In premenopausal women, benign elevations are particularly common.
Rangos de referencia normales
| Grupo | Rango | Unidad |
|---|---|---|
| Adults (general) | 0–35 | U/mL |
| Premenopausal women | 0–35 | U/mL |
| Postmenopausal women | 0–20 | U/mL |
Los rangos de referencia pueden variar entre laboratorios. Compara siempre tus resultados con los rangos proporcionados por tu laboratorio.
Qué significan los niveles altos de CA-125
Causas comunes
- Epithelial ovarian cancer (especially serous carcinoma)
- Endometriosis
- Uterine fibroids
- Pelvic inflammatory disease
- Menstruation and first trimester pregnancy
- Liver cirrhosis and ascites
- Peritoneal, pleural, or pericardial inflammation
- Endometrial, fallopian tube, and primary peritoneal cancers
- Pancreatitis and pancreatic cancer
- Congestive heart failure
Posibles síntomas
- Abdominal bloating or swelling
- Pelvic or abdominal pain
- Feeling full quickly when eating
- Urinary urgency or frequency
- Unexplained weight loss or gain
- Fatigue
- Back pain
Qué hacer: Elevated CA-125 requires clinical correlation. In postmenopausal women with an adnexal mass, elevated CA-125 strongly suggests malignancy and warrants surgical evaluation. In premenopausal women, benign causes should be excluded first. For patients with known ovarian cancer, serial CA-125 measurements are used to assess treatment response—a 50% decline correlates with response, while a doubling from nadir suggests progression. Additional imaging (transvaginal ultrasound, CT) and possibly further biomarkers (HE4, ROMA score) may be ordered.
Qué significan los niveles bajos de CA-125
Causas comunes
- Normal physiological state (no clinical concern)
- Successful treatment of ovarian cancer
- Non-mucinous ovarian cancers may not produce CA-125
Posibles síntomas
- No symptoms are associated with low CA-125
Qué hacer: Low or undetectable CA-125 is normal and generally reassuring. In ovarian cancer patients, declining CA-125 toward normal during chemotherapy indicates treatment response. However, a normal CA-125 does not exclude ovarian cancer—some histological subtypes (mucinous, clear cell) may not elevate CA-125 even in advanced disease.
¿Cuándo se recomienda la prueba de CA-125?
- Monitoring treatment response in epithelial ovarian cancer
- Surveillance for ovarian cancer recurrence after treatment
- Evaluating an adnexal mass in postmenopausal women
- Screening high-risk women (BRCA1/2 mutation carriers) in combination with ultrasound
- Assessing response to neoadjuvant chemotherapy in ovarian cancer
Preguntas frecuentes
Biomarcadores relacionados
Referencias y enfoque de revisión
Las páginas del glosario de biomarcadores son explicaciones educativas y deben interpretarse junto con los rangos de referencia y comentarios proporcionados por tu laboratorio y tu profesional de salud. Para conocer nuestros estándares editoriales y proceso de revisión, consulta nuestra Política editorial y nuestro Proceso de revisión de contenido.
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Subir resultados de laboratorio →Aviso médico: Esta información es solo educativa y no sustituye el consejo, diagnóstico ni tratamiento médico profesional. Los rangos de referencia pueden variar entre laboratorios. Consulta siempre a tu profesional sanitario para interpretar tus resultados concretos.