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Non-Small Cell Lung Cancer

Medically reviewed by Last updated on Aug 7, 2023.

What is Non-Small Cell Lung Cancer?

Harvard Health Publishing

One of the most common cancers, lung cancer usually occurs when a cancer-causing agent, or carcinogen, triggers the growth of abnormal cells in the lung. These cells multiply out of control and eventually form a tumor. As the tumor grows, it can block or narrow airways and make breathing difficult. Eventually, tumor cells can spread (metastasize) to nearby lymph nodes and other parts of the body. These include the

In most cases, the carcinogens that trigger lung cancer are chemicals found in cigarette smoke. However, more and more lung cancers are being diagnosed in people who have never smoked.

Lung cancers are divided into two groups: non-small cell lung cancer (NSCLC) and small cell lung cancer. NSCLC accounts for about 85% of all lung cancers. These cancers are further divided into subgroups, based on how their cells look under a microscope:

NSCLC is more likely than small cell cancer to be localized at the time of diagnosis. That means the cancer is limited to the lung or that it hasn’t spread beyond the chest. As a result, it can usually be treated with surgery. It may not respond well to chemotherapy (anticancer drugs). However, sophisticated genetic tests can help predict which patients may show favorable responses to particular treatments, including chemotherapy.

Unfortunately, even when doctors think that the cancer is localized, it often comes back after surgery. This means cancer cells had started to spread before surgery, but they couldn’t yet be detected.

Your risk of all types of lung cancer, including NSCLC, increases if you


In some cases, NSCLC is detected when a person with no symptoms has a chest x-ray or computed tomography (CT) scan for another reason. But most people with NSCLC have one or more of these symptoms:

If the cancer has spread beyond the lungs, it can cause other symptoms. For example, you may have bone pain if it has spread to your bones.

Many of these symptoms can be caused by other conditions. See your doctor if you have symptoms so that the problem can be diagnosed and properly treated.


Your doctor may suspect lung cancer based on

To look for evidence of cancer, your doctor will examine you, paying special attention to your lungs and chest. He or she will order imaging tests to check your lungs for masses. In most cases, a chest x-ray will be done first.

If the x-ray shows anything suspicious, a CT scan will be done. As the scanner moves around you, it takes many pictures. A computer then combines the images. This creates a more detailed image of the lungs, allowing doctors to confirm the size and location of a mass or tumor.

You may also have a magnetic resonance imaging (MRI) scan or a positron emission tomography (PET) scan. MRI scans provide detailed pictures of the body’s organs, but they use radio waves and magnets to create the images, not x-rays. PET scans look at the function of tissue rather than anatomy. Lung cancer tends to show intense metabolic activity on a PET scan. Some medical centers offer combined PET-CT scanning.

If cancer is suspected based on these images, more tests will be done to make the diagnosis, determine the type of cancer, and see if it has spread. These tests may include the following:

After the cancer has been diagnosed, it is assigned a "stage." Stages of NSCLC reflect the tumor’s size and how far the disease has spread. Stages I through III are further divided into A and B categories.

You may be tested for specific genetic mutations. Knowing about the presence of these mutations can help predict which therapy will be best. This strategy can be especially helpful in certain patients, such as women with adenocarcinoma of the lung who have never smoked.

Expected Duration

NSCLC will continue to grow and spread until it is treated. As with any cancer, even if it seems to be cured after treatment, NSCLC can return.


To reduce your risk of lung cancer,

The U.S. Preventive Services Task Force recommends annual screening for lung cancer with low-dose computed tomography in adults ages 55 to 80 years:

The decision to proceed with lung cancer screening is not straightforward. Many so called abnormalities found on CT scan are not cancerous. However patients will often undergo extensive testing, including surgery, to find out. CT scan screening is an individualized decision to be made with your doctor.


Surgery is the main treatment for NSCLC that has not spread beyond the chest. The type of surgery will depend on the extent of the cancer and the patient’s condition. It will also depend on whether other lung conditions, such as emphysema or COPD (chronic obstructive pulmonary disease), are present.

There are three types of surgery:

Lymph nodes are also removed and examined to see if the cancer has spread.

Some surgeons use video-assisted thoracoscopy (VATS) to remove small, early-stage tumors, especially if the tumors are near the outer edge of the lung. (VATS can also be used to diagnose lung cancer.) Because the incisions for VATS are small, this technique is less invasive than a traditional "open" procedure.

Because surgery will remove part or all of a lung, breathing may be more difficult afterwards, especially in patients with other lung conditions (emphysema, for example). Doctors can test lung function prior to surgery, which helps determine surgical risk and predict how lung function will be affected by surgery.

Depending on how far the cancer has spread, treatment may include chemotherapy (the use of anticancer drugs) and radiation therapy. These may be given before and/or after surgery.

When the tumor has spread significantly, chemotherapy may be recommended to slow its growth, even if it cannot cure the disease. Chemotherapy has been shown to ease symptoms and prolong life in cases of advanced NSCLC.

Radiation therapy can relieve symptoms, too. It is often used to treat NSCLC that has spread to the brain or bones and is causing pain. It can also be used alone or with chemotherapy to treat cancer that is confined to the chest. Unfortunately, chemotherapy and radiation therapy do not work as well against large cell lung cancer as they do against other non-small cell lung tumors.

People who may not withstand surgery due to other serious medical problems may receive radiation therapy, with or without chemotherapy, to shrink the tumor. A newer method of delivering radiation therapy, CyberKnife, uses highly focused beams of radiation. It requires fewer treatments than other types of radiation therapy.

In specialized cancer centers, cancerous tissue may be tested for specific genetic abnormalities (mutations). Doctors may then be able to treat the cancer with a "targeted therapy." These therapies can derail the cancer’s growth by preventing or changing chemical reactions linked to particular mutations. For example, some targeted therapies prevent cancer cells from receiving chemical "messages" telling them to grow.

When To Call a Professional

Call your doctor promptly if you have any symptoms of lung cancer, especially if you smoke or have had a job with high exposure to asbestos.

Current and former heavy smokers may want to ask their doctor a chest CT screening program may be right for them.


The outlook depends on the type of lung cancer, its stage, and the overall health of the patient. In general, the prognosis is poor, especially if the cancer has spread beyond the chest.

Additional Information

National Cancer Institute (NCI)

American Cancer Society (ACS)

American Lung Association

National Heart, Lung, and Blood Institute (NHLBI)

U.S. Environmental Protection Agency (EPA)

National Institute for Occupational Safety and Health

U.S. Department of Labor’s Occupational Safety & Health Administration (OSHA)

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.