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How Is Lung Cancer Diagnosed?

Getting a diagnosis of lung cancer often includes several steps and tests, and there is no single approach that is best for all people. To confirm lung cancer, a sample of tissue or fluid must be removed from the body and sent to a laboratory for examination. This process is called biopsy. In some cases, a diagnosis of lung cancer is made through surgery. During surgery, doctors can remove any tissue that is suspected of and looks like cancer, and that tissue will be sent to the laboratory for further testing.1

However, there may be several tests done prior to biopsy or surgery, including screening tests, which are done before symptoms are noticeable. Screening for lung cancer is done with imaging techniques such as spiral low-dose computed tomography (LDCT). There are screening guidelines for people at high risk for lung cancer to detect cancer in its earliest, and most treatable, stages.1

Screening may detect lung nodules – small, round masses of tissue that may be caused by cancer, infections, scar tissue, or other conditions. Depending on size and other features, nodules may be discovered and watched for changes upon further screenings, or further tests may be required to determine if they are cancerous.1

Some of the techniques and procedures used during a diagnosis of lung cancer include:

  • Laboratory tests, including a complete blood count, blood chemistry tests, and the tests completed on a biopsy sample 2
  • Imaging tests, including chest x-ray, CT (computed tomography) scans, PET (positron emission tomography) scans 2
  • Sputum cytology, in which a sample of mucus coughed up from the lungs is examined under the microscope 3
  • Thoracentesis, a procedure in which a needle or small tube is used to remove excess fluid in the pleural space, the space between the lungs and the chest wall 4
  • Needle biopsy, a procedure in which a sample of tissue is removed from the lungs to examine it for cancerous (malignant) cells 5
  • Bronchoscopy, a procedure in which a doctor views the airways (bronchi) with the use of a thin, lighted tube containing a camera and may take a tissue sample 6
  • Thoracoscopy, a minimally invasive surgical procedure in which a thin, lighted scope with a video camera is inserted into the chest through a small incision, allowing the surgeon to visually inspect and potentially to remove tissue samples for biopsy 7

Once a diagnosis of lung cancer has been confirmed, additional tests are conducted to learn more about the type of cancer and the effects of the cancer on the patient, including:

  • Additional imaging, such as a bone scan or brain MRI (magnetic resonance imaging)
  • Performance status, a numerical rating given to a patient’s ability to function in daily life, including the ability to care for oneself, engage in physical activity, and whether any assistance or medical care is necessary 8
  • Immunohistochemistry, laboratory testing that uses antibodies to test for certain markers, or antigens, in a sample of tissue 2
  • Molecular testing, laboratory testing done on a sample of a malignant tumor to detect genetic mutations 2
  • Pulmonary function testing, non-invasive tests that assess breathing and how well the lungs are working 9

Second Opinion

When the diagnosis is lung cancer, there is often a sense of urgency to begin treatment immediately. However, there is time for a second opinion, and because there are often multiple choices for treatment, second opinions can be helpful in providing more information and options. Some health care plans also require a second opinion.1

When seeking a second opinion, copies of all tests, including laboratory and imaging tests, must be gathered to send to the physician giving the second opinion. Some people feel uncomfortable asking for their tests from their first doctor, however, the test results belong to the patient. In addition, second opinions are standard in cancer care.1

Written by: Emily Downward | Last reviewed: January 2017.
  1. NCCN Guidelines for Patients. Non-Small Cell Lung Cancer. Version 1.2015. Accessed April 11, 2016 at:
  2. National Cancer Institute. Accessed online on 9/9/16 at
  3. American Cancer Society. Accessed online on 9/9/16 at
  4. National Heart, Lung, and Blood Institute, National Institutes of Health. Accessed online on 9/12/16 at
  5. MedlinePlus, U.S. National Institutes of Medicine. Accessed online on 9/12/16 at