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Lung cancer

Medically reviewed by Drugs.com. Last updated on Mar 31, 2023.

What is 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 destroys nearby areas of the lung. 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, relatively more lung cancers are being diagnosed in people who have never smoked. But this still accounts for a minority of new cases.

Lung cancers are divided into two groups, based on how their cells look under the microscope: non-small cell lung cancer and small cell lung cancer. Knowing whether the cancer has spread is critical, because it affects treatment decisions.

Non-small cell lung cancer may be localized. Localized lung cancer is limited to the lung and has not spread. It may be treated with surgery. Small cell lung cancer is rarely localized, even when it is detected early. It is rarely treated with surgery. 

However, even when doctors think that the cancer is localized, it often comes back after surgery. It can come back either in the location where it first started. Or it can recur in another part of the body. This usually means cancer cells had started to spread before surgery, but they couldn't yet be detected.

Non-small cell lung cancer

Non-small cell lung cancer is more likely than small cell cancer to be localized at the time of diagnosis. It also is more likely than small cell cancer to be treatable with surgery. It often responds poorly to chemotherapy (anticancer drugs). However, sophisticated genetic tests can help predict which patients may show favorable responses to particular treatments, including chemotherapy and newly developed targeted therapies.

Non-small cell lung cancer accounts for about 85% of all lung cancers. These cancers are divided into subgroups, based on how their cells look under a microscope:

Small cell lung cancer

At the time of diagnosis, small cell lung cancer is more likely than non-small cell cancer to have spread beyond the lung. This makes it almost impossible to cure with surgery. However, it can be managed with chemotherapy or radiation therapy. Small cell cancers account for about 15% of all lung cancers.

Lung cancer risk factors

Your risk of all types of lung cancer increase if you

Symptoms

In some cases, lung cancer 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 lung cancer 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.

Certain small cell lung cancers may secrete chemicals that can alter the body's chemical composition. For example, levels of sodium and calcium may be abnormal. This can lead to the diagnosis of small cell lung cancer.

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.

Diagnosis

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:

Lung cancer

After the cancer has been diagnosed, it is assigned a "stage." The stages differ for non-small cell lung cancer and small cell lung cancer.

Non-small cell lung cancer stages

Stages of non-small cell lung cancer reflect the tumor's size and how far the cancer has spread. Stages I through III are further divided into A and B categories.

Small cell lung cancer stages

Many experts divide small cell lung cancers into two groups:

Knowing the type of cancer and its stage helps doctors determine the best treatment. Limited stage cancer, for example, may be treated with surgery and/or chemotherapy. Extensive stage cancer is much less likely to be cured.

Expected duration

Lung cancer will continue to grow and spread until it is treated.

Prevention

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 50 to 80 years:

Treatment

After lung cancer has been diagnosed, the type of treatment depends on the type of cancer and how much the tumor has spread (its stage).

Non-small cell lung cancer

Surgery is the main treatment for non-small cell lung cancers that have not spread beyond the chest. The type of surgery will depend on the extent of the cancer. It will also depend on whether other lung conditions, such as emphysema, 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 and predict how it might be affected by surgery.

Genetic testing of the tumor evaluates whether there are mutations that cause the cancer to grow and spread. If present, specific drugs are now available to treat these mutations and have provided encouraging results in some patients.

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 and/or immunotherapy may be recommended to slow its growth, even if it cannot cure the disease. These therapies have been shown to ease symptoms and prolong life in cases of advanced lung cancer.

Radiation therapy can relieve symptoms, too. It is often used to treat lung cancer that has spread to the brain or bones and is causing pain. It can also be used alone or with other therapies to treat the lung cancer that is confined to the chest.

People who may not withstand surgery due to other serious medical problems may receive radiation therapy, with or without chemotherapy, as an alternative to surgery. Advances in radiation have made it possible for prolonged survival in some people, with results similar to surgery.

Knowing about specific genetic 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.

Small cell lung cancer

The treatment of small cell lung cancer depends on its stage:

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.

Prognosis

The outlook depends on the type of lung cancer, its stage, and the overall health of the patient.

Additional info

National Cancer Institute (NCI)
https://www.nci.nih.gov/

American Cancer Society (ACS)
https://www.cancer.org/

American Lung Association
https://www.lung.org


Learn more about Lung cancer

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Further information

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