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Can Lung Cancer Be Found Early?

Screening is the use of tests or exams to find a disease in people who don’t have symptoms. 

Regular chest x-rays have been studied as a screening test for people at higher risk for lung cancer, but they haven't been shown to help most people live longer, and therefore they aren't recommended for lung cancer screening.

At this time, a test known as a low-dose CT (LDCT) scan is used to screen people people at higher risk for lung cancer (mainly because they smoke or used to smoke). LDCT scans can help find abnormal areas in the lungs that may be cancer. Research has shown that unlike chest x-rays, yearly LDCT scans to screen people at higher risk of lung cancer can save lives. For these people, getting yearly LDCT scans before symptoms start helps lower the risk of dying from lung cancer.

Reasons to screen people at higher risk for lung cancer

In the United States, lung cancer is the second most common cancer. It’s also the leading cause of death from cancer.

If lung cancer is found at an earlier stage, when it is small and before it has spread, it is more likely to be treated successfully.

Lung cancer screening is recommended for certain people who smoke or used to smoke, but who don't have any signs or symptoms.

Usually symptoms of lung cancer don't appear until the disease is already at an advanced stage. Even when lung cancer does cause symptoms, many people may mistake them for other problems, such as an infection or long-term effects from smoking. This may delay the diagnosis. If you have symptoms that could be from lung cancer, see your doctor right away. (People who already have symptoms that might be from lung cancer may need tests such as CT scans to find the cause, which in some cases may be cancer. But this kind of testing is for diagnosis and is not the same as screening.)

American Cancer Society guideline for lung cancer screening

The American Cancer Society recommends yearly screening for lung cancer with a low-dose CT (LDCT) scan for people aged 50 to 80 years who:

  • Smoke or used to smoke


  • Have at least a 20 pack-year history of smoking

A pack-year is equal to smoking 1 pack (or about 20 cigarettes) per day for a year. For example, a person could have a 20 pack-year history by smoking 1 pack a day for 20 years, or by smoking 2 packs a day for 10 years.

Before deciding to be screened, people should have a discussion with a healthcare professional about the purpose of screening and how it is done, as well as the benefits, limits, and possible harms of screening. 

People who still smoke should be counseled about quitting and offered interventions and resources to help them. 

People should not be screened if they have serious health problems that will likely limit how long they will live, or if they won’t be able to or won’t want to get treatment if lung cancer is found.

Benefits and possible risks of lung cancer screening

The main benefit of screening is the chance to find lung cancer earlier, which can lower your risk of dying from lung cancer.

Still, it’s important to be aware that, as with any type of screening, not everyone who gets screened will benefit. Screening with LDCT will not find all lung cancers. Not all of the cancers that are found will be found at an early stage. And some people with lung cancer found by screening will still die from that cancer.

LDCT scans can also find things that turn out not to be cancer, but that still have to be checked out with more tests to know what they are. You might need more CT scans, or less often, invasive tests such as a lung biopsy, in which a piece of lung tissue is removed with a needle or during surgery. These tests might lead to serious complications, although this is rare.

LDCTs also expose people to a small amount of radiation with each test. It is less than the dose from a standard CT, but it is more than the dose from a chest x-ray. Some people who are screened may end up needing further CT scans, which means more radiation exposure.

Other things to consider if you're thinking about screening

If you are at higher risk for lung cancer, your doctor can explain your risk and how lung cancer screening might apply to you. Your doctor can also talk with you about what happens during screening and the best places to get the yearly screening test. Lung cancer screening is covered by Medicare and by many private health insurance plans. Your health care team can help you find out if your insurance will provide coverage.

Screening should only be done at facilities that have the right type of CT scanner and that have experience in LDCT scans for lung cancer screening. The facility should also have a team of specialists that can give patients the appropriate care and follow-up if there are abnormal results on the scans. You might not have the right kind of facility nearby, so you may need to travel some distance to be screened.

If you smoke, you should get counseling about stopping. You should be told about your risk of lung cancer and referred to a smoking cessation program. Screening is not a good alternative to stopping smoking. By quitting, people who smoke can lower their risk of getting and dying from lung cancer. For help quitting, see How To Quit Smoking and Smokeless Tobacco or call the American Cancer Society at 1-800-227-2345.

To get the most benefit from screening, people need to be in fairly good health. For example, they need to be healthy enough (and willing) to have surgery and get other treatments if lung cancer is found. People who have other major health issues that could keep them from having lung surgery might not be good candidates for lung cancer screening. The same is true for people who might have a shortened life expectancy because they already have other serious medical conditions. These people might not benefit enough from screening for it to be worth the risks.

It's important to talk to your doctor about all your health issues when deciding if lung cancer screening is right for you.

How screening is done

As noted above, screening for lung cancer is done with a yearly low-dose CT scan (LDCT). For this test, you lie on a thin, flat table that slides back and forth inside the hole in the middle of the CT scanner, which is a large, doughnut-shaped machine.

As the table moves into the opening, an x-ray tube rotates within the scanner, sending out many tiny x-ray beams at precise angles. These beams quickly pass through your body and are detected on the other side of the scanner. A computer then converts these results into detailed images of the lungs.

An LDCT scan is painless and only takes a few minutes, although the entire visit (including getting you ready and into place on the table) can take up to half an hour. You don’t need to swallow anything or get any type of injection before this type of CT scan. As noted above, LDCT does expose you to a small amount of radiation, although it is less than that from a standard CT scan.

To learn more about CT scans and what getting one is like, see CT Scan for Cancer

If something abnormal is found during screening

Sometimes screening tests will show something abnormal in the lungs or nearby areas. Most of these abnormal findings will turn out not to be cancer, but more CT scans or other tests will be needed to be sure. Some of these tests are described in Tests for Lung Cancer.

CT scans of the lungs can also sometimes show problems in other organs near the lungs. Your doctor will discuss any such findings with you if they are found.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

The American Cancer Society acknowledges the Society of Thoracic Radiology for providing their expert collaboration and the LDCT images used in the development of our animated lung cancer screening content. 

Aberle DR, Adams AM, Berg CD, et al; National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011;365(5):395-409.

de Koning HJ, van der Aalst CM, de Jong PA, et al. Reduced lung-cancer mortality with volume CT screening in a randomized trial. N Engl J Med. 2020;382(6):503-513.

National Cancer Institute. Physician Data Query (PDQ). Patient Version. Lung Cancer Screening. 2019. Accessed at on August 27, 2021.

Wolf AMD, Oeffinger KC, Shih YCT, et al. Screening for lung cancer: 2023 guideline update from the American Cancer Society. CA Cancer J Clin. 2023. doi:10.3322/caac.21811.

Last Revised: November 1, 2023