Lung cancer

Definition

Lung cancer is cancer that starts in the lungs.

The lungs are located in the chest. When you breathe, air goes through your nose, down your windpipe (trachea), and into the lungs, where it flows through tubes called bronchi. Most lung cancer begins in the cells that line these tubes.

There are two main types of lung cancer:

If the lung cancer is made up of both types, it is called mixed small cell/large cell cancer.

If the cancer started somewhere else in the body and spreads to the lungs, it is called metastatic cancer to the lung.

Alternative Names

Cancer - lung

Causes

Lung cancer is the deadliest type of cancer for both men and women. Each year, more people die of lung cancer than of breast, colon, and prostate cancers combined.

Lung cancer is more common in older adults. It is rare in people under age 45.

Smoking causes most cases (around 90%) of lung cancer. The risk depends on the number of cigarettes you smoke each day and for how long you have smoked. Being around the smoke from other people (secondhand smoke) also raises your risk of lung cancer. The risk does decrease with time after you stop smoking. But some people who have never smoked do develop lung cancer. There is no evidence that smoking low-tar cigarettes lowers the risk.

Research shows that smoking marijuana may help cancer cells grow. But there is no direct link between smoking marijuana and developing lung cancer.

Constant exposure to high levels of air pollution and drinking water that has a high level of arsenic can increase your risk of lung cancer. A history of radiation therapy to the lungs can also increase risk.

Working with or living near cancer-causing chemicals or materials can also increase the risk of developing lung cancer. Such chemicals include:

Symptoms

Early lung cancer may not cause any symptoms.

Symptoms depend on the type of cancer you have, but may include:

Other symptoms that may also occur with lung cancer, often in the late stages:

These symptoms can also be due to other, less serious conditions, so it is important to talk to your health care provider.

Exams and Tests

Lung cancer is often found when an x-ray or CT scan is done for another reason.

If lung cancer is suspected, your provider will perform a physical exam and ask about your medical history. You will be asked if you smoke. If so, you'll be asked how much you smoke and for how long you have smoked. You will also be asked about other things that may have put you at risk for lung cancer, such as exposure to certain chemicals.

When listening to the chest with a stethoscope, the provider may hear fluid around the lungs. This may suggest cancer.

Tests that may be done to diagnose lung cancer or see if it has spread include:

In most cases, a piece of tissue is removed from your lungs for examination under a microscope. This is called a biopsy. There are several ways to do this:

If the biopsy shows cancer, more imaging tests are done to find out the stage of the cancer. Stage means how big the tumor is and how far it has spread. Staging helps guide treatment and follow-up and gives you an idea of what to expect.

Treatment

Treatment for lung cancer depends on the type of cancer, how advanced it is, and how healthy you are:

The above treatments may be done alone or in combination. Your provider can tell you more about the specific treatment you will receive, depending on the specific type of lung cancer and what stage it is.

Support Groups

You can ease the stress of illness by joining a cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.

Outlook (Prognosis)

How well you do depends mostly on how much the lung cancer has spread.

When to Contact a Medical Professional

Contact your provider if you have symptoms of lung cancer, particularly if you smoke.

Prevention

If you smoke, now is the time to quit. If you are having trouble quitting, talk with your provider. There are many methods to help you quit, from support groups to prescription medicines. Also, try to avoid secondhand smoke.

References

American Cancer Society website. Key statistics for lung cancer. www.cancer.org/cancer/types/lung-cancer/about/key-statistics.html. Updated January 17, 2024. Accessed January 25, 2024.

American Lung Association website. Lung cancer trends brief. www.lung.org/research/trends-in-lung-disease/lung-cancer-trends-brief. Accessed January 25, 2024.

Araujo LH, Horn L, Merritt RE, Shilo K, Xu-Welliver M, Carbone DP. Cancer of the lung: non-small cell lung cancer and small cell lung cancer. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 69.

Centers for Disease Control and Prevention website. Health problems caused by secondhand smoke. www.cdc.gov/tobacco/secondhand-smoke/health.html. Updated November 1, 2022. Accessed August 29, 2023.

National Cancer Institute website. Non-small cell lung cancer treatment (PDQ) - health professional version. www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq. Updated February 17, 2023. Accessed July 23, 2023.

National Cancer Institute website. Small cell lung cancer treatment (PDQ) - health professional version. www.cancer.gov/types/lung/hp/small-cell-lung-treatment-pdq. Updated December 8, 2023. Accessed January 25, 2024.

Pastis NJ, Gonzalez AV, Silvestri GA. Lung cancer: diagnosis and staging. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 76.


Review Date: 1/25/2022
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Internal review and update on 07/23/2023 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 01/25/2024.
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