Doctors may order one or more kinds of laboratory tests to acquire information about a person's overall health and help in the determination of whether a person has lung cancer.

Blood tests

Blood tests do not diagnose lung cancer, but they provide a doctor information on a patient’s overall health and information on how well the organs of the body are functioning.

A complete blood count (CBC)A measure of the number of red blood cells, white blood cells, and platelets in the blood is ordered to check for:

  • Anemia, a low number of red blood cells
  • Thrombocytopenia, a low number of platelets, which can cause bleeding
  • Neutropenia, a low number of white blood cells (WBCs)A type of blood cell that is made in the bone marrow and found in the blood and lymph tissue. White blood cells are part of the body’s immune system. They help the body fight infection and other diseases., which can put a patient at increased risk for infection1

Blood chemistry testsA common panel of blood tests that measures the amounts of electrolytes and other chemicals made in the body are used to check whether a patient’s liver or kidneys are working well. The results from these blood tests help the doctor decide if a patient is able to undergo surgery or receive another type of lung cancer treatment.1,2

Sputum cytology

If lung cancer is suspected, sputum cytologyExamination under a microscope of cells found in sputum brought up from the lungs by coughing. The test checks for abnormal cells, such as lung cancer cells may be performed. The patient may be asked to cough up phlegmThick mucus made by the cells lining the upper airways and lungs so a pathologistA doctor who identifies diseases by studying cells and tissues under a microscope or with other equipment can look at it under a microscope. A doctor usually orders a patient to provide phlegm three mornings in a row. A pathologist can locate cancer cells in the mucus, but most of the time there are not enough cells to make a final diagnosis of lung cancer. In addition, there is a high rate of false negatives with this test—that is, the test often does not detect cancer when cancer is actually present.2,3

Sputum cytology is more likely to help diagnose lung cancers that start in the major airways of the lung, such as most squamous cell lung cancersA type of non-small cell lung cancer that usually starts near a central bronchus. It begins in squamous cells, which are thin, flat cells that look like fish scales.. It may not be as helpful for finding other types of lung cancers. It also does not provide information on how far the disease has spread, so if it is positive for lung cancer other diagnostic tests must be performed.2,3

Updated February 12, 2024


  1. “Complete Blood Count tests. Cancer.Net website. Approved September 2022. Accessed February 5, 2024.
  2. Tests for Non-Small Cell Lung Cancer. American Cancer Society website. Revised November 20, 2023. Accessed February 5, 2024.
  3. Sputum Cytology. website Reviewed January 2017. Accessed February 5, 2024.