Laboratory Tests

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There are several laboratory tests that may be done during the diagnosis and staging of lung cancer. Laboratory tests are any procedure that evaluates a sample of blood, urine, other bodily fluid, or tissue. Some tests provide specific information about a condition, while others rule out other problems (determine other problems don’t exist) or provide general information about the patient’s overall health.1

While there is not a single laboratory test that can determine if a person has lung cancer (confirmation of lung cancer occurs after lung cells are examined through a microscope), the tests can provide additional information that helps doctors determine the best course of treatment for the individual.2

Complete Blood Count (CBC)

A complete blood count is a test that measures all the different components in the blood. Blood contains several different cells: red blood cells, white blood cells, and platelets. The complete blood count measures the levels of these cells, as well as the levels of hemoglobin (an iron-rich protein in red blood cells that carries oxygen), hematocrit (a percentage representing the space that red blood cells occupy in the blood) reticulocyte count (a percentage representing the number of young red blood cells in the blood), and mean corpuscular volume (the average size of red blood cells).3

Some of the abnormal findings from a CBC include:

  • Low levels of red blood cells can indicate anemia
  • Low levels of blood platelets can point to a tendency to bleed and difficulty forming clots
  • Low levels of white blood cells can place a person at higher risk for infections 2

In addition to completing a CBC during diagnosis, CBC is often completed during chemotherapy courses to monitor side effects of treatments.2

Blood Chemistry Tests

Blood chemistry tests detect various levels of substances in the body and can identify abnormalities in some of the organs. If lung cancer has spread, it can change the functional ability of the organ in which it spreads to, creating an imbalance in the levels of markers found in the blood, such as electrolytes, metabolites, fats, and proteins, including enzymes.1,2

Biopsy

Tissue samples that have been collected during a needle biopsy or thoracoscopy are taken to the laboratory for testing. These tissue samples are viewed under a microscope by a pathologist, a physician who specializes in the diagnosis of diseases based on analyzing bodily fluids or tissues. Cancerous cells can be identified by their appearance. In some cases, the samples are also treated with proteins that attach to specific sites in cancer cells, followed by treating the proteins with a substance causing changes in color to make them more easily identifiable under the microscope.1,2

Genetic Tests

Some laboratory tests that may be done on tissue samples include genetic tests, or molecular tests. These look for specific genetic mutations in cancer cells. Positive test results can inform doctors about targeted treatments to treat the cancer. Some common genetic mutations in lung cancer include epidermal growth factor receptor (EGFR), KRAS, and ALK.2