Healthcare providers can use a CA-125 blood test as a component of an overall strategy to monitor ovarian cancer therapy. 

Other Names

CA125 (Cancer Antigen 125)

Cancer Antigen 125

Carbohydrate Antigen 125

OV Monitor

Cancer Ag 125 (CA 125)

CA25

What is a CA-125 test?

The CA-125 test measures the level of the protein CA-125, also known as cancer antigen 125, in your blood. CA-125 is a biomarker, indicating a substance in your blood that might signal a condition or disease. A high CA-125 level can suggest ovarian cancer, considering that the ovaries, responsible for egg storage, and hormone production, are involved.

However, the CA-125 test can yield both false positives and false negatives. Elevated CA-125 levels may not always indicate cancer (false positive), and normal levels may not rule out cancer (false negative). Therefore, the CA 125 test isn’t an effective standalone screening method for ovarian cancer.

Healthcare providers typically incorporate the CA 125 test into a broader monitoring strategy for certain cancers, especially during and after cancer treatment. It’s also employed for early detection in individuals at high risk, such as those with a family history of ovarian cancer or a genetic predisposition. However, for those without symptoms or risk factors, the CA-125 test isn’t considered useful.

When is the CA-125 test done?

A CA-125 blood test can serve the following purposes:

1. Assessing Treatment Effectiveness: It helps measure whether the treatment for ovarian cancer is effective. A decreasing CA 125 level over time generally indicates that the cancer treatment is working.

2. Monitoring for Recurrence: The test is used to monitor the potential recurrence of ovarian cancer after successful treatment. This monitoring typically occurs at regular intervals, such as every few months or every year, depending on when the treatment was completed.

Normal Results

Your healthcare provider should interpret your results as acceptable ranges can vary, and different labs may use different tests. Typically, levels exceeding 35 units per milliliter are considered irregular. However, it’s important to note that elevated levels don’t necessarily indicate cancer or a cancer recurrence. To understand the implications of your results and assess whether additional testing is necessary, it’s crucial to have a discussion with your healthcare provider.

False Positive Results

Various conditions other than ovarian cancer can result in a “positive” CA-125 test score. These include:

• Menstruation.
• Pregnancy.
• Endometriosis.
• Pelvic inflammatory disease (PID).
• Uterine fibroids or other benign (noncancerous) growths.
• Other cancers such as pancreatic or fallopian tube cancer.
• Liver disease.

Due to the potential for elevated CA 125 levels in these conditions, a CA 125 test is not used as a standalone diagnostic tool. Instead, it is employed in conjunction with other diagnostic methods to provide a more comprehensive understanding of the individual’s health and potential presence of ovarian cancer.

References

1. (N.d.). Retrieved from https://www.mayocliniclabs.com/test-catalog/overview/9289 
2. professional, C. C. medical. (n.d.). Retrieved from https://my.clevelandclinic.org/health/diagnostics/17830-ca-125-blood-test