CA 15-3

Overview

CA 15-3 (Cancer Antigen 15-3) is a circulating fragment of the MUC1 glycoprotein found on epithelial cells. The blood test measures the level of this tumor-associated antigen. It is most commonly used in the context of breast cancer to monitor disease burden, treatment response, and detect recurrence rather than as a population screening tool. Elevated levels may suggest breast cancer (especially metastatic disease) but can also occur with other malignancies (ovary, lung, liver, pancreas) and benign conditions (liver disease, benign breast disease, pregnancy). Levels can vary with age, liver function, and physiologic states; it is used mainly in adult women with known or suspected breast cancer.

Test Preparation

• Overnight fasting (8-12 hrs) is required
• Do not eat or drink anything except water before the test
• Do not stop taking your thyroid medications on the day of the test unless otherwise advised by the doctor
• Avoid iron supplements for at least 24 hours prior to sample collection
• For CA 125, CA 15
• 3 and CEA- Provide brief clinical history/doctor's prescription at the time of sample collection
• CA 125 test should not be done immediately before or during menstruation or immediately after abdominal surgery, as these cause transiently increased levels
• Pregnancy may also affect the levels of CA 125
• The urine sample must preferably be the first morning midstream urine (part of urine that comes after the first and before the last stream)
• Collect the urine sample in a sealed and sterile screw-capped container provided by our sample collection professional
• Ensure that the urethral area (from where the urine is passed) is clean & container doesn't come in contact with your skin
• Women are advised not to give the sample during the menstrual period unless prescribed
• You should submit all the required samples for this package at once during the scheduled sample collection
• For the USG Whole Abdomen test: A
• Overnight fasting (8-12 hours) is required
• Do not eat or drink anything except water before the test
• B
• Drink plenty of water before the USG procedure to ensure a full bladder
• For ECG: A
• Remove any metal objects that may interfere with the electrodes
• If you have a pacemaker or other implanted cardiac devices, inform the technician
• B
• Wear comfortable clothing that allows easy access to your chest area, and avoid using oils, lotions, or creams on your chest area on the test day
• C
• Avoid consuming large amounts of caffeine (coffee, tea, energy drinks) before the test
• For X-ray: A
• Depending on the area to be imaged, you may be asked to wear a hospital gown at the time of the scan
• B
• You may have to remove your jewelry and any metal objects that might interfere with the image
• C
• Pregnant women should inform their doctor (and x-ray technician) as the radiation may affect the fetus
• If needed, precautions can be taken to lower the radiation exposure to the fetus
• For PAP smear: Refrain from sexual activity for 2 to 5 days before the sample collection

Why Do I Need This Test

• Which profile is the test included in: Cancer screening / tumor marker panels - Symptoms indicating testing: new breast lump, unexplained weight loss, bone pain, respiratory symptoms, or clinical suspicion of recurrence - Conditions it may diagnose/monitor: monitoring known breast cancer, detecting recurrence or progression, occasionally adjunct for other epithelial cancers - Reasons for abnormal levels: tumor burden/metastasis, benign breast disease, liver dysfunction, pregnancy, other cancers - Biological meaning: higher levels generally reflect greater tumor load or cell turnover - Behaviors/lifestyle/family history: chronic liver disease (alcohol, hepatitis), and family history of breast cancer may increase the need for monitoring

Understanding Test Results

• Values ≤30 U/mL are generally considered within the normal range.
• Mild elevations (roughly 30–60 U/mL) may reflect early or localized disease, benign breast conditions, or non-malignant liver pathology.
• Moderate elevations (about 60–100 U/mL) raise concern for active malignancy or metastatic involvement.
• Marked elevations (>100 U/mL) are often associated with advanced or metastatic breast cancer.
• Rapidly rising values over serial measurements are more clinically meaningful than a single mildly elevated result.
• Low values are not clinically significant.
• False positives occur with liver disease, pregnancy, and other cancers; sensitivity and specificity are limited, so interpretation requires clinical context and imaging.

FAQs