A complete blood count measures your red and white blood cells and platelets. While this blood test gives doctors a wide range of important medical information, it can’t detect breast cancer.

A complete blood count (CBC) is a common part of breast cancer treatment. Doctors typically order a CBC before treatment to get an idea of your baseline blood counts.

Doctors also use CBCs during treatment to ensure your blood cell levels aren’t dropping. The CBC will alert doctors if levels are too low and you’ll be treated before you experience side effects.

Learn more about how CBCs are used before and during breast cancer treatment, and the tests doctors use to detect and diagnose breast cancer.

A CBC measuresTrusted Source the levels and health of your white blood cells, red blood cells, and platelets. It’s an important marker of your health and is frequently done before cancer treatments are started.

Doctors may alsoTrusted Source order additional blood tests to determine if there are cancer antigens in the blood and learn more about your genetics. For example:

  • Blood chemistry tests: These tests look at the levels of certain chemicals in your blood. They’re a good measure of how your organs are functioning and may be used to help stage your cancer.
  • Tumor marker tests: These tests look for the presence of cancer antigens in the blood. A cancer antigen is a protein found in cancer cells. However, cancer isn’t the only thing that can cause these antigens, and not everyone with breast cancer will have cancer antigens.

Symptoms of cancer and treatments such as radiation and chemotherapy can affectTrusted Source the levels of blood cells in your body. Checking before treatment begins gives doctors an idea of your baseline. They check again during your treatments to monitor your blood count levels.

If chemotherapy or radiation is causing your level of red blood cells, white blood cells, or platelets to drop, you can receive medications alongside your treatments to help prevent side effects of low blood counts, such as anemia.

After treatment ends, a CBC can help doctors get a look at your overall health and make sure you’re not experiencing any negative reactions to medications.

A CBC can’t detect or diagnose breast cancer, but there are tests that will confirm a diagnosis. Often, a physical exam of breast tissue and a review of your medical history will be the first step. From there, a doctor might recommend testing, includingTrusted Source:

  • Diagnostic mammogram: A diagnostic mammogram is an imaging test that creates detailed images of the breast.
  • Ultrasound: An ultrasound uses sound waves to create close-up images that help doctors determine if an abnormality in breast tissue is a tumor or a cyst.
  • Biopsy: A biopsy is the only way to confirm a diagnosis of breast cancer. A biopsy procedure involves removing a small amount of tissue from the lump or abnormal area and then having that tissue tested for cancer in a lab. Typically, a biopsy is an outpatient procedure. However, sometimes surgical biopsies that remove the entire lump are performed.
  • Lymph node biopsy: If a doctor suspects your cancer has spread to your lymph nodes, they might be surgically removed and then tested for cancer.

The exact requirements for breast cancer screening depend on your overall risk and your age.

Starting at age 40, the U.S. Preventative Services Task Force (USPSTF) recommends mammogram screening every two years for those at average risk.

Screenings should continue as long as the person remains in good health. However, some people who are at a higher risk, such as people who have the BRCA1 and BRCA2 genes are advised to begin yearly screenings earlier.

Most cancers are detected when imaging tests, such as CT scans or MRIs, spot tumors or signs of organ damage.

However, blood cancers, such as leukemia, raise white blood cell counts and can be detected in a CBC. Other tests will still be needed to confirm a diagnosis.

A CBC is a common test that can help doctors get a snapshot of your overall health. It can also be used to look for:

  • leukemia
  • lymphoma
  • anemia
  • infection
  • the effects of certain medications

A CBC measures the components of your blood. This includes:

  • Red blood cells: Red blood cells transport oxygen throughout your body.
  • White blood cells: Your body uses white blood cells to fight infection.
  • Hemoglobin: Hemoglobin are proteins inside your red blood cells.
  • Hematocrit: Hematocrit is the fluid, or plasma in your red blood cells.
  • Platelets: Platelets are what allow your blood to clot.

A complete blood count (CBC) is a test that can help doctors get a picture of your overall health. It’s often used to check for infections, and it can help detect some blood cancers.

Although a CBC can’t detect breast cancer, it’s used before and during breast cancer treatment. Chemotherapy and radiation can destroy blood cells. A CBC can check blood cell levels. If your levels drop during treatment, medication can help bring them up so that you don’t experience side effects.

After treatments are finished, a CBC is a good marker of whether you’ve returned to your baseline, and a good way to ensure you’ve not experienced any negative reactions to medications.