CA125 Tumour Marker Blood Test: Normal & Dangerous Range

What is CA125?

CA125, also known as cancer antigen 125, is a protein-sugar complex (glycoprotein) found on the cell surface of ovaries, fallopian tubes, peritoneum, pleura, colon, kidney and stomach. CA125 is a biomarker that detects certain conditions or diseases.

High levels of CA125 may indicate various conditions, including ovarian cancer, endometriosis, pelvic inflammatory disease (PID), or other benign conditions affecting the reproductive organs. However, CA125 levels alone cannot diagnose specific conditions, as they can vary for many reasons due to many factors. This test is typically used alongside other diagnostic tools and physical examinations to help healthcare providers make accurate diagnoses.

Learn more about the most common gynaecological conditions in Singapore here.

What are the causes of raised CA125 levels?

Elevated CA125 levels usually points to:

• The presence or development of cancers (cancers of fallopian tubes, pancreas and peritoneum)

• Indicates conditions such as endometriosis, diverticulitis, liver cirrhosis, pregnancy and uterine fibroids

• However, the levels of CA125 does not reflect  the severity of cancers and diseases

Monitoring CA125 levels also proves to be an effective way to monitor recurrent ovarian cancer in women who have previously been treated for it and determine the response to treatment of ovarian cancer.

What type of cancer does CA125 detect?

Ovarian cancer

CA125 is most commonly used to detect epithelial ovarian cancer. Elevated levels of CA125 are found in approximately 80% - 90% of patients with advanced-stage disease.

Endometrial cancer

CA125 is also used in diagnosing endometrial cancer, as high levels of CA125 can indicate this type of cancer as well.

Fallopian tube cancer

Similar to ovarian cancer, elevated CA-125 levels can suggest the presence of fallopian tube cancer.

Other cancers

Elevated CA-125 levels may also be seen in:

• Pancreatic cancer

• Breast cancer

• Colorectal cancer

• Lung cancer

• Stomach cancer

What CA125 level indicates cancer?

The normal range of CA125 is 0-35 units/ml. While a CA125 level over 35 units/ml may indicate cancer, however, this is not a sure-fire way to diagnose cancer as high levels of CA125 can be caused by other conditions too, it is just a potential indicator for doctors to conduct further tests to make a diagnosis.

If a woman has been previously treated for ovarian cancer and CA125 levels are high again, it may indicate that the ovarian cancer has returned. More tests are needed to make the diagnosis.

Can CA125 be high without cancer?

Yes, CA125 levels can be elevated due to non-cancerous conditions. Some common benign causes of high CA125 include:

• Endometriosis: A condition where the tissue that lines the uterus grows outside of it.

• Pelvic inflammatory disease (PID): Infections of the reproductive organs.

• Pregnancy: CA125 levels may increase during the first trimester.

• Liver diseases: Such as cirrhosis.

• Menstrual cycle: Hormonal changes during menstruation can sometimes lead to elevated CA125.

Since many non-cancerous conditions can raise CA125 levels, this biomarker alone cannot definitively indicate cancer. Your doctor may use imaging scans or additional diagnostic tests to understand the cause of the elevated levels.

Think that you might have the above conditions? Contact our specialists at Thomson Medical today to get diagnosed and discuss your options. Request for an appointment today.

How is CA125 measured? 

CA125 is measured through a simple blood test, where a healthcare provider takes a sample of blood from a vein in your arm. The sample is then analysed in a laboratory to determine the levels of CA125 in your bloodstream.

The procedure for a CA125 test

1. Preparation: No special preparation is usually required for the test. However, inform your doctor about any medications or supplements you are taking, as they may influence the results.

2. Blood draw: A nurse or phlebotomist will insert a small needle into your vein and collect a small amount of blood in a tube.

3. Lab analysis: The blood sample is sent to a laboratory, where specialists measure the concentration of CA125 in units per millilitre (U/ml).

4. Results: You will receive your results within a few days. Your healthcare provider will interpret these results alongside other tests and your medical history to provide a comprehensive diagnosis.

When should you get a CA125 test?

The CA125 test is used to screen for ovarian cancer and other conditions. It is usually ordered by the doctor in the following scenarios: 

• If you experience persistent pelvic or abdominal pain.

• Unexplained bloating or changes in bowel habits.

• As a screening test for individuals who are at higher risk of developing ovarian cancer (family history of ovarian or related cancers).

• To monitor the effectiveness of ovarian cancer treatment. A decrease in CA125 levels over time is observed if the treatment is effective.

• To monitor if ovarian cancer comes back after successful treatment. This is usually done every few months to every year, depending on when you finished your treatment.

• To help diagnose ovarian cancer.

Want to find out more about CA125 testing at Thomson Medical? Get in touch with us here.

How reliable is the CA125 test?

The CA125 test is a valuable tool for monitoring ovarian cancer, particularly in tracking recurrence or treatment response, but it has its limitations when used as a diagnostic tool. Here’s why:

• Sensitivity and specificity: The test has a high sensitivity for detecting ovarian cancer in advanced stages but lower sensitivity for early-stage cancers.

• False positives: Many benign conditions can cause elevated CA125 levels, leading to false positives.

• False negatives: Not all ovarian cancer patients have elevated CA125 levels, particularly in early stages.

To improve accuracy, doctors typically combine the CA125 test with other diagnostic tools, such as pelvic ultrasounds or transvaginal ultrasounds, for a more accurate diagnosis.

What happens if CA125 is positive?

If your CA125 levels are above the normal range (over 35 units/ml), your doctor will take a detailed approach to investigate further:

1. Review of medical history and symptoms: Your doctor will consider your overall health, family history of cancer, and symptoms such as abdominal pain, bloating, or unexplained weight loss.

2. Additional diagnostic tests: Your doctor is likely to order additional tests to investigate further. Such tests include:

   • Imaging scans: Ultrasound, CT scans, or MRI to identify abnormalities in the ovaries or other organs.

   • Biopsy: A sample of tissue may be taken to confirm the presence of cancer.

3. Monitoring: If you have a history of ovarian cancer, a rise in CA125 levels may indicate a recurrence, prompting your doctor to order further tests.

Next steps: Elevated CA125 levels do not automatically mean you have cancer, but they do warrant further evaluation to determine the underlying cause.

Can CA125 levels be reduced?

Elevated CA125 levels caused by underlying conditions often decrease once the condition is treated. Here are some scenarios:

• Treating cancer: Chemotherapy, surgery, or other cancer treatments often reduce CA125 levels in cancer patients.

• Managing benign conditions: Addressing endometriosis or infections like PID may lower CA125 levels.

Regular follow-ups with your doctor are essential to monitor CA125 levels and ensure effective treatment.

Understanding CA125 levels can provide valuable insights into your health. Whether you're monitoring a known condition or investigating unexplained symptoms, our specialists at Thomson Medical are here to provide expert advice and personalised care. Request for an appointment with our specialists today to take the first step towards better health.

FAQ

What does a CA125 test for?

A CA125 test measures the levels of cancer antigen 125 (CA125) in the blood. It is used to:

• Monitor treatment response in ovarian cancer.

• Detects recurrence of ovarian cancer.

• Aid in diagnosing other conditions, such as endometriosis, pelvic inflammatory disease (PID), or uterine cancer, when combined with other tests.

What level of CA-125 is concerning?

While no specific CA125 level definitively confirms uterine cancer, significantly elevated levels (above 35 units/ml) may suggest further investigation. Uterine cancer may lead to higher CA125 levels, but diagnosis requires additional tests, such as imaging or a biopsy, to confirm. Elevated levels are not always indicative of cancer, as non-cancerous conditions such as pregnancy, menstruation, or infections can also cause high CA125 levels.

Can CA125 predict early-stage ovarian cancer?

While CA125 is more reliable for advanced stages, its effectiveness for early detection is limited.

Can men take a CA125 test?

Yes, although rare, elevated CA125 levels in men may indicate pancreatic or lung cancer.

What is a normal CA125 level?

A normal level is 0–35 Units/ml.

Should I worry if my CA125 is slightly elevated?

Slightly elevated levels may not always indicate a serious problem. Many non-cancerous conditions, such as menstruation, pregnancy, or minor inflammation, can cause a mild increase.  Your doctor will evaluate the results alongside other diagnostic tools.

Who should get a CA-125 blood test?

A CA-125 blood test is recommended to those with increased risk of ovarian cancer. People who are at higher risk of ovarian cancer usually:

• Are carriers of the BRCA gene.

• Have a biological family member with ovarian cancer.

• Had ovarian cancer in the past.

If your doctor thinks that you may have ovarian cancer or is currently treating you for ovarian cancer, a CA-125 test may be used to monitor your condition.

When should I get a CA-125 blood test?

CA-125 blood test is recommended in the following scenarios:

• As a screening test for those with high risk of developing ovarian cancer

• To measure if the treatment for ovarian cancer is working. If the levels are going down over time, it means that the cancer treatment is working.

• To monitor if ovarian cancer comes back after successful treatment. This is usually done every few months to every year, depending on when you finished your treatment.

• To help with the evaluation of a person who has symptoms of ovarian cancer or is suspected of having ovarian cancer.

Disclaimer: The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, consult a specialist by requesting an appointment with Thomson Medical today.