Can Cancer Be Detected by a Blood Test?

Reviewed on 4/27/2021
cancer blood test
Certain blood tests can help guide a cancer diagnosis

If your physician suspects cancer during physical examination or while taking a medical history, they might order certain cancer blood tests to guide the diagnosis. These blood tests are called tumor markers. Tumor markers could be specifically raised in certain cancers, and may give some idea about the origin of cancer and whether it is responding to the treatment protocol. These tests, however, are neither specific for certain cancers nor highly sensitive.

Other blood tests could be ordered. While these may not detect cancer or benign tumors, they can give a general idea about the functioning of the organ and indicate whether it has been affected by cancer.

What types of blood tests can help detect cancer?

Tumor marker tests

Tumor markers are chemicals produced by cancer cells and found in the blood. However, tumor markers are also made by normal cells in the body, and levels may increase significantly in noncancerous conditions. Examples of tumor markers include:

Circulating tumor cell tests

Recently developed blood tests can detect tumor cells that have separated from an original cancer site and are flowing through the bloodstream. The United States Food and Drug Administration (U.S. FDA) has approved one circulating tumor cell test to monitor people with breast, colorectal or prostate cancer. However, these tests are not commonly used in a clinical setting.

Blood protein testing

Electrophoresis is a test that examines various proteins in the blood. This can help identify various immunoglobulins, which are elevated in people with multiple myeloma. A bone marrow biopsy may help confirm the diagnosis of blood cancer.

Complete blood count (CBC)

A complete blood count helps the doctor to:

  • Diagnose some blood cancers, such as leukemia and lymphoma.
  • Find out if cancer has invaded the bone marrow.
  • Look how a person’s body handles cancer treatment.
  • Diagnose other noncancerous conditions.

The results of CBC are interpreted as:

A bone marrow biopsy may help confirm the diagnosis of blood cancer.


Urinalysis is a lab examination of urine for various cells and chemicals, such as red blood cells, white blood cells, infection or excessive protein. Blood in the urine may indicate a benign condition, but it can also indicate other problems.

Other blood tests include:

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Mayo Clinic. Cancer Blood Tests: Lab Tests Used in Cancer Diagnosis.

Stanford Health Care. Urine Test – Urinalysis.

The University of Iowa Hospitals and Clinics. Cancer Diagnostic Tests and Blood Tests Word List.

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