Lung Cancer - Non-Small Cell: Diagnosis

Aprobado por la Junta Editorial de Cancer.Net, 11/2021

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread, but they can never be used alone to diagnose NSCLC. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Lung cancer cannot be detected by routine blood testing, but blood tests may be used to identify genetic mutations in people who are already known to have lung cancer (see "Biomarker testing of the tumor" below).

How NSCLC is diagnosed

There are many tests used for diagnosing NSCLC. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

Finding out where the cancer started

NSCLC starts in the lungs. Many other types of cancer start elsewhere in the body and spread to the lungs when they metastasize. For example, breast cancer that has spread to the lungs is still called breast cancer. Therefore, it is important for doctors to know if the cancer started in the lungs or elsewhere.

To find where the cancer started, your doctor will take into account your symptoms and medical history, physical examination, how the tumor looks on x-rays and scans, and your risk factors for cancer. A pathologist can perform tests on the biopsy sample to help find out where the cancer began. Your doctor may recommend other tests to rule out specific types of cancer. If, after these considerations, the doctor is still not sure where the cancer started, the doctor may give a diagnosis of metastatic cancer “of unknown primary.” Most treatments for metastatic cancer of unknown primary that are first found in the chest are the same as those for metastatic lung cancer.

The following tests may be used to diagnose and learn the stage of lung cancer:

Imaging tests

Imaging scans are very important in the care of people with NSCLC. However, no test is perfect, and no scan can diagnose NSCLC. Only a biopsy can do that (see below). Chest x-ray and scan results must be combined with a person’s medical history, a physical examination, blood tests, and information from the biopsy to form a complete story about where the cancer began and if or where it has spread.

  • Computed tomography (CT or CAT) scan. A CT scan produces images that allow doctors to see the size and location of a lung tumor and/or lung cancer metastases. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

  • Positron emission tomography (PET) scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.

  • Magnetic resonance imaging (MRI) scan. An MRI also produces images that allow doctors to see the location of a lung tumor and/or lung cancer metastases and measure the tumor’s size. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. However, MRI scanning does not work well to take pictures of parts of the body that are moving, like your lungs, which move with each breath you take. For that reason, MRI is rarely used to look at the lungs. It may be helpful to find lung cancer that has spread to the brain or bones.

  • Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image. PET scans (see above) have been replacing bone scans to find NSCLC that has spread to the bones.

The procedures that doctors use to collect tissue to diagnose lung cancer and plan treatment are listed below:

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. It is helpful to have a larger tumor sample to determine the subtype of NSCLC and do additional molecular testing (see below). If not enough of the tumor is removed to do these tests, another biopsy may be needed. After the biopsy, a pathologist analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

  • Bronchoscopy. In a bronchoscopy, the doctor passes a thin, flexible tube with a light on the end into the mouth or nose, down through the main windpipe, and into the breathing passages of the lungs. A surgeon or a pulmonologist may perform this procedure. A pulmonologist is a medical doctor who specializes in the diagnosis and treatment of lung disease. The tube lets the doctor see inside the lungs. Tiny tools inside the tube can take samples of fluid or tissue so the pathologist can examine them. Often, lymph nodes will be examined and biopsies will be taken using an ultrasound to guide the bronchoscopy. This is called an endobronchial ultrasound (EBUS). Patients are given mild anesthesia during a bronchoscopy. Anesthesia is medication to block the awareness of pain.

  • Needle aspiration/core biopsy. After numbing the skin, a special type of radiologist, called an interventional radiologist, removes a sample of the lung tumor for testing. This can be done with a smaller needle or a larger needle depending on how large of a sample is needed. The doctor uses the needle to remove a sample of tissue for testing. Often, the radiologist uses a chest CT scan or special x-ray machine called a fluoroscope to guide the needle. In general, a core biopsy provides a larger amount of tissue than a needle aspiration. As explained above, doctors have learned that more tissue is needed in NSCLC for diagnosis and molecular testing.

  • Thoracentesis. After numbing the skin on the chest, a needle is inserted through the chest wall and into the space between the lung and the wall of the chest where fluid can collect. The fluid is removed and checked for cancer cells by the pathologist.

  • Thoracoscopy. This procedure is performed in the operating room, and the patient receives general anesthesia. Through a small cut in the skin of the chest wall, a surgeon can insert a special instrument and a small video camera to assist in the examination of the inside of the chest. Patients need general anesthesia for this procedure, but recovery time may be shorter with a thoracoscopy because of the smaller incisions that are used. This procedure may be referred to as video-assisted thoracoscopic surgery or VATS. Another kind of minimally invasive surgery called "robotic-assisted surgery" maybe done instead of a thoracoscopy.

  • Mediastinoscopy. This is a surgical procedure performed in the operating room, and the patient receives general anesthesia. A surgeon examines and takes a sample of the lymph nodes in the center of the chest underneath the breastbone by making a small incision at the top of the breastbone. This procedure also requires general anesthesia and is done in an operating room.

  • Thoracotomy. This procedure is performed in an operating room, and the patient receives general anesthesia. A surgeon then makes an incision in the chest, examines the lung directly, and takes tissue samples for testing. A thoracotomy is rarely used to diagnose lung cancer, but it may be necessary to completely remove a lung tumor.

Biomarker testing of the tumor

Your doctor may recommend running tests on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. This may also be called molecular testing of the tumor.

There are several genes that may have changes, called mutations, in a lung tumor that can help the cancer grow and spread. These mutations are found in the tumor and not in healthy cells in the body. This means they are not inherited or passed down to your children.

Results from these tests and information about the stage of NSCLC you have can help determine if you can receive targeted therapy, which can be directed at specific mutations (see Types of Treatment). Targeted therapies now exist for many different genetic mutations that are known to cause lung cancer and research is ongoing to develop more (see Latest Research).

Genetic mutations that are known to contribute to lung cancer growth often occur on 1 or more of several genes, including EGFR, ALK, KRAS, BRAF, HER2, ROS1, RET, MET, and TRK and testing the tumor for these genes is now common. Certain mutations that can be treated with targeted therapy are much more likely to occur in people with adenocarcinoma NSCLC and those who never smoked. However, people whose have a history of smoking may also have genetic mutations that can be treated with targeted therapy, therefore, it is essential to test for molecular mutations, regardless of a history of smoking.

Your doctor may also recommend PD-L1 testing. PD-L1 is a protein found on the surface of some cancer cells and some of the body's immune cells. This protein stops the body's immune cells from destroying the cancer. Knowing if the tumor has PD-L1 will help your doctor decide if certain types of immunotherapy are more or less likely to be helpful (see Types of Treatment).

Currently, there are different biomarker tests that can be done to determine if you have any genetic changes.

Comprehensive biomarker testing. Tissue that is removed during the biopsy to diagnose NSCLC should also be tested for the different possible genetic mutations that can contribute to lung cancer. This is called "comprehensive biomarker testing" and may be referred to generally as "biomarker testing."

Sometimes, there may not be enough tissue to test for all of the mutations. Your health care team may decide to test for the most likely changes or they may need to do another biopsy to get enough tissue.

Liquid biopsy. A type of blood test called a "liquid biopsy" is being used more and more to help diagnose specific genetic changes in people with NSCLC. This test looks for a type of DNA called "circulating tumor DNA." Like healthy cells, cancer cells die and are replaced. When these dead cells break down, they are released into the bloodstream. A liquid biopsy can detect the small pieces of DNA in the bloodstream from these cells.

Liquid biopsies are less invasive than other types of biopsies and have less risks. Liquid biopsies can be done as a part of your initial diagnosis and they can be done multiple times throughout treatment. Your doctor can use this test to check on the progress of a tumor and see how well treatment is working.

After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.

Coping with a NSCLC diagnosis

For most patients, a diagnosis of NSCLC is extremely stressful. Some people who are diagnosed with NSCLC develop anxiety and, less commonly, depression. You and your families should not be afraid to talk with the health care team about how you feel. The health care team has special training and experience that can make things easier for patients and their families and is there to help.

In addition to providing information and emotional support, your doctor may include supportive services and palliative care specialists in your care. This team could include a counselor, psychologist, social worker, or psychiatrist.

You and your family may also find resources available in the community to help people living with lung cancer, such as support groups. Some patients feel comfortable discussing their disease and experiences throughout treatment with their health care team, family, friends, or other patients through a support group. These patients may also join a support group or advocacy group in order to increase awareness about lung cancer and to help fellow patients who are living with this disease.

A NSCLC diagnosis is serious. However, doctors can offer effective treatment for the cancer. In addition, advances being made in the diagnosis and treatment of NSCLC that provide more and more patients with a chance for cure.

Learn more about the counseling, finding a support group, and being a cancer advocate.

Stopping smoking

Even after NSCLC is diagnosed, it is still beneficial to quit smoking. People who stop smoking have an easier time with all treatments, feel better, live longer, and have a lower risk of developing a second lung cancer or other health problems. It is never easy to stop smoking and even harder when facing the diagnosis of NSCLC. If you smoke, seek help from family, friends, programs for quitting smoking, and health care professionals. None of the products available to quit smoking interfere with cancer treatment. Learn more about stopping tobacco use after a cancer diagnosis in a separate section of this website.

The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.