Cancer Antigen 15.3 (CA 15.3) Test

CA 15-3 (cancer antigen 15-3) is a protein produced by normal breast cells. Many patients with cancerous breast tumours produce an increased amount of CA 15-3.

CA 15-3 is not responsible for cancer, but instead, it is released by tumour cells and enters the bloodstream after the tumours grow. This CA 15-3 test measures antigen CA 15-3 in the blood.

It is commonly known as a tumour marker. The tumour mark is elevated in women who have relapsed breast cancer after treatment. It is needed to monitor the treatment of breast cancer.

CA 15-3 test is used to see how well breast cancer treatment is working. To detect recurrence or a return of cancer, the CA 15-3 test is the most important one.

The CA 15-3 test value is elevated in about 80% of women whose breast cancer has spread to other parts of the body and fewer women with early symptoms of breast cancer or with a small tumour.

Higher CA 15-3 levels are typically related to more advanced stages of breast cancer when the cancer is spread to the liver, bone, etc.

Consequently, women with detected breast cancer may not always have high levels of CA 15-3, as there are other conditions too that yield false-positive results for the CA 15-3 test.

So it is always important to correlate the CA 15-3 test with a physical examination, blood tests and other diagnostic imaging to avoid false-positive results.

Moreover, CA 15-3 is not a first screening diagnostic test for screening breast cancer, as there are chances this may also be elevated in healthy people as well as in individuals suffering from another type of cancer such as colon, lung, prostate, etc.

The CA 15-3 test requires a blood sample for testing. The blood sample is taken from a vein in the hand. A lab technician will collect samples at the laboratory.

The CA 15-3 test does not need any fasting before sample collection. Although, talking to your doctor is required for details of instructions.

Breast cancer, Breast cancer metastasis, Breast cancer recurrence

The CA 15-3 ideally measures levels of cancer antigen 15-3 in the blood sample. It is advised by your doctor along with some tests if there is a doubt of breast cancer.

Some of the common conditions when the CA 15-3 test is prescribed are:

• Among women with a history of breast cancer.
• In women who are under treatment for breast tumours.
• Those at risk of breast cancer.
• A new lump in or around the breast.
• The breast is swollen.
• Redness of the nipples and flakiness of nipple tissue.
• Pulling type of pain in the breasts heaviness of the breasts.
• Water or bloody discharge from nipples.
• Continuous pain in the breast.
• In case of metastasis, to monitor prognosis.

This CA 15-3 test is also prescribed to

• Confirm what kind of treatment or therapies in combination will work for breast cancer.
• Figure out the prognosis of treatment.
• Predict probabilities of recovery and chances of cancer returning.

The CA 15-3 test applies to men and women. The doctor will ask for this test in young girls and adult women with a history of breast cancer.

The significance of CA 15-3 in men is comparatively less.

CA 15-3 test helps determine cancer characteristics and decide on treatment options.

CA15-3 is a cancer marker. Since CA 15-3 can be detected in the blood sample, it is a tumour marker to assess the prognosis of cancer. This test is repeated based on your symptoms and as per your doctor’s advice. Usually, it is repeated every 2-3 months based on the prognosis of cancer.

A cancer specialist (oncologist) or gynaecologist will prescribe a CA 15-3 test. In case of a history of breast cancer, you may need to repeat the CA 15-3 test more frequently. The repetition of the test is needed as and when a concerned doctor advises. Repetition is essential for detecting breast cancer recurrence.

Before the Test

Typically, your doctor will not ask you to take special measures for a CA 15-3 test. However, if you are scheduled for this test along with another one, your healthcare provider may recommend fasting or avoiding certain foods. Always consult a doctor before the test for guidance.

During the Test

When the phlebotomist arrives for the CA 15-3  test, a blood sample will be drawn from a vein in your arm. Here's what you can expect during the test:

• The area where the needle will be inserted will be cleaned with antiseptic.
• A tourniquet will be tied to your upper arm to make your veins visible.
• A needle will be inserted into the vein to draw the blood. This process may cause a brief pinch lasting a few seconds.
• The blood will be collected in a vial or small test tube, and a label will be filled with your details.

After the Test

Following the blood collection:

• A bandaid will be placed over the insertion site to stop any bleeding.
• Bruising is a common after effect. Some people also feel dizzy. You may be advised to rest for a few minutes.
• If bleeding, pain, or rashes at the puncture site persist, it's important to contact your healthcare provider.

The CA 15-3 test measures the values of CA 15-3 antigens in the blood sample.

The CA 15-3 reports include these two variables:

• Higher levels of cancer antigen 15-3 which means CA 15-3 positive.
• Low levels or normal levels of cancer antigen 15-3 means CA 15-3 is negative.

Women with CA 15-3 positive results might have a recurrence of breast cancer. It also indicates the spread of existing breast cancer in other parts of the body. Females with CA 15-3 negative reports indicate that the body is healing well with cancer treatment and better recovery.

CA 15-3 values use units per millilitre (U/mL) for measurement.

• Males: <30 U/mL (usually not defined)
• Females: <30 U/mL

Whether your CA 15-3 results are in the normal range or not is determined by your age, gender, method of test and other factors. Talk to your doctor if the values are beyond CA 15-3 normal range.

The normal values and reference ranges of the test may vary from lab to lab. Please refer to the ranges mentioned in the report and consult a doctor to understand the interpretation of lab reports.

CA 15-3 Test results may differ based on age, gender, history, test method and other factors. Increased levels of CA 15-3 do not mean there is an underlying issue. In all cases, it is advisable to discuss the interpretation of test results with the specialist.

CA 15- 3 test positive or higher than normal:

CA15-3 levels are higher, which indicates that breast cancer has progressed to other regions of the body. The spread is known as metastasis of breast cancer.

Though, CA 15-3 levels do not rise in all forms of breast cancer because some cancer cells do not overproduce this antigen.

CA 15-3 test values increase as the cancer cells grow. In metastatic cancer, when the breast cancer has spread to other parts like bone, liver, etc., the level of CA 15-3 is much higher, concentrations tend to increase as cancer grows.

If the CA 15-3 value increases, each repetition means the cancer tissue is not responding well to treatment and cancer might reappear.

Although, there are multiple factors responsible for false-positive CA 15-3.

False-positive results of CA 15-3 can be seen in the following conditions:

• Some cancerous growth in the ovaries, liver and breast
• Endometriosis
• Liver diseases
• Pelvic inflammatory disease (PID).
• Pregnancy shows a high level of CA 15-3.

CA15-3 may be higher than the normal range in:

Lung cancer

• Pancreatic cancer
• Ovarian cancer
• Prostate cancer
• Cervical cancer
• Colonic cancer

But these levels are not as high as with breast cancer and final interpretations depend upon clinical history. Increasing values of CA 15-3 are signs of either Ca breast progression or recurrence in general.

CA 15- 3 test negative or lower:

CA 15-3 lower value than the normal range indicates no cancer or regression of the carcinoma of the breast.

If the CA 15-3 value gradually reduces or returns to normal, it is an indication that treatment is working well on cancer and there are fewer chances of its recurrence.