Tumor marker tests: what they are and what the results show

A referral for a blood test for tumor markers is often frightening: it seems that a single number on the form will immediately answer the main question. In reality, it is only one of the tools, and it must be read together with other examinations. Let us calmly explain what this test is and what to expect from it.

What tumor markers are

A tumor marker is a substance that is present in the body or produced by cancer cells or other cells of the body in response to cancer or certain benign conditions. Such substances are found in blood, urine, stool, tumor and other tissues or fluids. Traditionally, these are proteins and other substances that cancer cells produce in greater quantities than normal cells. Genomic markers are also increasingly used — mutations in tumor genes, features of their expression, changes in tumor DNA.

An elevated marker level by itself does not mean cancer: benign conditions can also raise it, and not every person with a certain cancer has an elevated marker. Therefore, measurements are usually combined with biopsy and imaging.

What types of tumor markers exist

Many markers have been described, and some of them are associated with one type of cancer, others with several. Among those frequently measured: AFP (alpha-fetoprotein) — a marker of hepatocellular liver cancer; PSA (prostate-specific antigen) — a marker of prostate cancer; CA-125 — a marker of ovarian cancer; CEA (carcinoembryonic antigen) — a marker of rectal cancer. Some tumor-specific non-coding RNAs, such as PCA3, are also classified as tumor markers.

The tests are performed in laboratories that comply with established quality standards. In addition to blood and urine, the material may be a tissue fragment obtained by biopsy — in that case, we are talking about tumor cell markers.

How to take a blood test for tumor markers

Blood is the most common option for such a test. Blood is drawn from a vein in the arm with a small needle into a tube; the procedure usually takes less than five minutes, and mild pain or a bruise at the puncture site is possible and resolves quickly. Special preparation for a blood test is usually not required. If a biopsy is planned, fasting for several hours may be needed — this should be discussed with the doctor in advance.

A stool test for tumor markers and a urine test are also possible: for urine, the midstream method is used with hygienic preparation, and in case of bleeding hemorrhoids or menstruation, this should be reported before collection. A tumor marker test does not replace a biopsy: it is the biopsy that confirms or rules out cancer.

Tumor markers for women

Among the markers is CA-125 — a marker of ovarian cancer; AFP, as has historically been found, is also elevated in malignant ovarian diseases. At the same time, tumor marker tests are mainly used after a diagnosis has been established: to assess the extent of the process, estimate the growth rate and likelihood of recurrence, select treatment and monitor its effectiveness. They play a limited role in people at high risk — with a family history or environmental and behavioral factors — and in symptoms resembling a certain type of cancer.

Why a result may be elevated not only in cancer

Some non-cancerous conditions also cause high levels of certain markers, and the test cannot distinguish where exactly the substance came from. The opposite also happens: in a person with confirmed cancer, the marker is not elevated. During treatment, a decrease in level usually indicates that therapy is helping. A separate subtlety: with successful treatment and tumor shrinkage, tissue breakdown may temporarily increase the concentration of markers in the blood.

• A high marker in the absence of cancer is possible in benign conditions.
• A normal marker in cancer also happens; the test is not universal.
• A temporary rise in the marker during successful treatment is possible due to breakdown of tumor tissue; the doctor assesses it together with other examinations.
• Screening by a single marker is unreliable: the tests are not sensitive and specific enough.

Is ferritin a tumor marker

Ferritin is not included in the list of frequently measured tumor markers given above. If ferritin appears on the form next to tumor markers, it is a separate indicator, and its result is assessed by a doctor, not a "cancer test".

An elevated tumor marker by itself is not a reason to call an ambulance; 103 or 112 — in a life-threatening condition, for example if a stroke or heart attack is suspected.

The material is for reference and does not replace a doctor's consultation: it is better to discuss the results and further steps with an oncologist or family doctor.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer