The Best Blood Test for Cancer

Samples taken for cancer blood tests are tested in a lab for signs of cancer. When viewed under a microscope, the samples may show the actual cancer cells. Other blood tests might find proteins or other substances made by the cancer. Blood tests can also tell your provider how well your organs are working.

Most blood tests aren’t used on their own to diagnose cancer. But they can provide clues that may lead your health care team to make the diagnosis. For most types of cancer, a procedure to remove a sample of cells for testing is often needed to be sure.
Some blood tests used to diagnose cancer include:
A test to count your blood cells. A complete blood count (CBC) measures the amount of each type of blood cell in a sample of your blood. Blood cancers may be found using this test.
A test that looks at the blood proteins. An electrophoresis blood test looks at the various proteins in your blood to find the ones made by your body’s germ-fighting immune system. This test is helpful in diagnosing multiple myeloma.
Tests to find chemicals made by cancer cells. Tumor marker tests use a sample of blood to look for chemicals made by cancer cells.ests to look for cancer cells. Circulating tumor cell tests detect cancer cells in your blood. The cells might be in the blood if they’ve broken away from where they started and are spreading to other parts of the body. Circulating tumor cell tests are mostly used after a cancer diagnosis.
Not every person with cancer needs a circulating tumor cell test. These tests are sometimes used for a few types of cancer, including breast cancer, colon cancer and prostate cancer. Researchers are looking at how these tests might help people with other types of cancer.