CA-125 Test: Complete Guide to Ovarian Cancer Marker

By Dr. Pawan Gaba | LabDecoded

📑 Table of Contents

• What is CA-125?
• Why is the test done?
• Normal Range
• Causes of High CA-125
• Interpretation
• Limitations
• Conclusion

Quick Summary: CA-125 is a tumor marker mainly used for monitoring ovarian cancer, not for routine screening.

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What is CA-125?

CA-125 is a tumor marker used in ovarian cancer evaluation and monitoring. It is a glycoprotein derived from coelomic epithelium.

• Monitoring treatment
• Detecting recurrence
• Supporting diagnosis

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Why is the CA-125 Test Done?

Suspected Ovarian Cancer

• Pelvic mass
• Bloating
• Weight loss

Monitoring Treatment

• Chemotherapy response
• Disease progression

Recurrence Detection

• Rising levels indicate relapse

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Normal Range

Parameter	Value
CA-125	0–35 U/mL

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Causes of Elevated CA-125

Malignant

• Ovarian cancer
• Endometrial cancer
• Breast cancer

Benign

• Endometriosis
• Menstruation
• Pregnancy
• Liver disease

👉 Key Point: CA-125 is not cancer-specific.

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Interpretation Strategy

• 35–100 U/mL: Likely benign
• 100–500 U/mL: Suspicious
• >500 U/mL: Strong malignancy suspicion

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Limitations

• Low specificity
• Not for screening
• False positives common

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Conclusion

CA-125 is useful for monitoring ovarian cancer but must always be interpreted with imaging and clinical findings.

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📚 Read More:

• CBC Test Interpretation
• LFT Test Guide
• Tumor Markers Overview

🔍 Keywords:

CA-125 test, ovarian cancer marker, CA125 normal range, tumor markers, lab test interpretation