CA 125 (ovarian cancer marker)

CA 125 (Cancer Antigen 125) is a blood test that measures the concentration of a specific protein called CA 125 in the bloodstream. Although CA 125 is known as a tumor marker for ovarian cancer, it is important to understand that elevated levels do not always indicate cancer. This test is a valuable tool in the diagnosis of ovarian cancer, monitoring treatment effectiveness, and assessing the risk of disease recurrence.

What is CA 125 and why is it important?

CA 125 is a protein produced by certain cells, including those of the ovaries, uterus, fallopian tubes, pancreas, liver, and lungs. While a small amount of CA 125 in the blood is considered normal, its concentration may increase significantly in the presence of certain medical conditions, particularly ovarian cancer.

It is important to emphasize that CA 125 is not specific to ovarian cancer. Its level can also be elevated due to a variety of benign conditions. Therefore, this test is not used as a standalone method for diagnosing cancer but rather as an additional diagnostic tool.

When is a CA 125 test performed?

The CA 125 test is most commonly recommended in the following situations:

• To assist in the diagnosis of ovarian cancer: when a woman experiences symptoms that may suggest ovarian cancer (e.g., abdominal bloating, abdominal pain, early satiety, or urinary symptoms), or when an ovarian mass is detected during an ultrasound examination.
• To monitor the effectiveness of ovarian cancer treatment: after surgery or chemotherapy, decreasing CA 125 levels may indicate that the treatment is effective.
• To monitor for ovarian cancer recurrence: following successful treatment, regular monitoring of CA 125 levels may help detect a possible recurrence at an early stage.
• For risk assessment: in some women at high risk of ovarian cancer (e.g., due to BRCA gene mutations or a strong family history), CA 125 testing may be used in combination with other examinations, such as transvaginal ultrasound, as part of a surveillance program.

What do CA 125 test results mean?

CA 125 levels are measured in units per milliliter (U/mL).

• Normal CA 125 level: typically less than 35 U/mL. This suggests a low likelihood of ovarian cancer but does not completely rule it out.
• Elevated CA 125 level: may indicate ovarian cancer, but it can also be increased for many other reasons, including:
• • Benign gynecological conditions: endometriosis, uterine fibroids, pelvic inflammatory disease, and ovarian cysts;
  • Pregnancy;
  • Menstruation;
  • Liver disease;
  • Pancreatitis;
  • Cancers of other organs: pancreatic, gastric, lung, or breast cancer.

It is important to note that even in cases of ovarian cancer, approximately 20% of women with early-stage disease may have normal CA 125 levels. Therefore, this test is not suitable as a screening tool for ovarian cancer in the general population.

How should I prepare for a CA 125 test?

In most cases, no special preparation, such as fasting, is required before the test. However, it is always important to inform your doctor about any medications, vitamins, or supplements you are taking, as well as any existing medical conditions or recent illnesses.

How is a CA 125 test performed and how long does it take?

The CA 125 test is a simple blood test. A healthcare professional will collect a small blood sample from a vein, usually in the arm. The blood draw itself takes only a few minutes.