Tumor marker tests look for evidence of cancer in your blood, urine, or body tissues. In medical terms, a tumor marker is a substance present in the tissues, body fluids, blood, and bone marrow. It may be a sign of cancer. Moreover, it is a protein that is made by both healthy and cancerous cells in the body.

Your doctor may use a tumor marker test to investigate your chance of cancer. A tumor marker can be a genetic mutation, changes in tumor DNA or RNA, and patterns of gene expression. In general, oncologists use different tumor marker tests for cancers in different parts of the body. Also, many cancers cannot be detected using these tests. Plus, cancer diagnosis through a tumor marker test may not be as precise as other tests.

Why it’s done

Tumor marker tests are used by doctors to investigate the symptoms of cancer, its growth, and its severity. High levels of tumor markers are a sign of cancer. Therefore, these tests help the doctor to do the following.

To detect cancer

As a part of your initial cancer diagnosis, a tumor marker may be used. A high tumor marker level may indicate cancer. For example:

• A high level of prostate-specific antigen (PSA) implies prostate cancer. This is because PSA is normally found in the blood of males in low concentrations.
• A high level of CA 125 implies cancer of the ovary, uterus, pancreas, liver, cervix, lung, colon, or breast.
• An elevation in the level of carcinoembryonic antigen (CEA) implies cancer of the colon or rectum.
• A high level of Alpha-Fetoprotein (AFP) implies ovarian cancer, cancer of the colon, or testicles.
• An elevation in the level of human chorionic gonadotropin (HCG) implies pregnancy initially. If such a condition is ruled out, there can be a chance of cancer of the testis, stomach, pancreas, liver, and lung.
• A high level of CA 19-9 implies cancer of the stomach, bile duct, pancreas, or colon.
• A high level of CA 15-3 indicates breast cancer, ovarian cancer, prostate cancer, or lung cancer.
• A rise in the level of neuron-specific enolase (NSE) implies cancer of the lung (small-cell).

To decide the cancer treatment plan

Once cancer is diagnosed, a treatment plan is prepared by the oncologist. Some tumor markers explain which treatment can be more effective. Basically, a tumor marker is itself a protein whose level is elevated by cancer cells. Therefore, detection of the tumor marker helps in deciding the right treatment strategy. It helps in determining which therapy can work well.

To check the progress of cancer treatment

Changes in the levels of your tumor markers can demonstrate the effect of cancer medications or therapies. A significant decrease in tumor marker level indicates the progress of cancer treatment and helps the doctor to make relevant modifications in the treatment plan. If no difference is observed after a few months of using a therapy, your doctor may change your medicines.

To predict the chance of cancer recurrence

Periodic tumor marker tests during cancer treatment help your doctor in determining the behavior of cancer and its growth. Moreover, with the changing levels of tumor markers, your doctor can predict the chance of cancer recurrence (cancer that comes back after successful treatment).

How it’s done

Tumor marker tests can be conducted in different ways. The method depends upon the substance or sample to be examined for tumor markers. Mostly, a sample of blood, urine, or tissues is examined.

Before the procedure

You may not require any special preparations before a tumor marker test if your blood or urine sample needs to be collected during the procedure. However, your doctor will ask you to not eat anything a few hours before the procedure if a tissue sample needs to be collected.

During the procedure

• If your doctor recommends a blood test, a small needle will be used to collect a sample of blood from a vein in your arm. The lab technician will store this sample in a test tube or a vial for further examination. This procedure may take less than 10 minutes.
• If your doctor recommends a urine test, you will have to submit a sample of urine as per your doctor’s instructions. Preferably, you will be asked to collect the sample early in the morning so that dilution can be avoided.
• If your doctor recommends a biopsy, a tissue sample will be removed or shaved from your skin. If the sample needs to be collected from inside your body, your doctor may use a special needle to do the same. Sometimes, surgery may be required.

After the procedure

Once the sample for the test is collected, you may experience:

• Little pain or bruising at the site where the needle has been inserted to draw out blood if it was a blood test.
• No reaction after the submission of the sample if it was a urine test.
• Discomfort, bruising, and pain at the biopsy site if it was a surgical biopsy.

Results

Your doctor will examine the sample and look for the levels of tumor markers. Furthermore, if the results are abnormal, other diagnostic tests will be recommended depending upon the area to be examined.

Measurements used in Reports

• IU: international units
• mg/dL: milligrams per deciliter
• mL: milliliter
• cmm: cells per cubic millimeter
• g/dL: grams per deciliter
• mmol/L: millimoles per liter
• ng/mL: nanograms per milliliter
• fL: fraction of one-millionth of a liter
• pg: one-trillionth of a gram
• U/ml: units per milliliter
• IU/L: international units per liter
• mEq/L: milliequivalent per liter

Consult your doctor if you have any questions regarding the risks of tumor marker tests.

NOTE: Taking cancer medicines online without a prescription is a restricted activity. This article does not encourage you to skip any medical treatment or appointment. Make sure to follow the guidelines provided by your medical team.