Lung Cancer Screening Benefits and Risks

Lung cancer screening can help detect cancer in the lungs before it becomes symptomatic. If you are at risk for developing lung cancer, being screened can be an effective way to catch the disease early, begin treatment promptly, and perhaps even cure it.

a doctor showing a patient her tablet
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Who Should Be Screened?

Lung cancer develops as a result of damage to cells in the lungs, typically due to exposure to a carcinogen (a substance that can cause cancer) of some sort. Cigarette smoke is a leading cause of lung cancer, but there are many other potential causes of the disease, including second-hand smoke and radon and other environmental toxins.

Family history may also play a role in the development of lung cancer. Other factors can increase your vulnerability to lung cancer, such as HIV infection.

Although there are many risk factors for lung cancer, screening is advised for a very specific group of people.

The U.S. Preventive Services Task Force (USPSTF) recommends yearly screening for lung cancer using low-dose computerized tomography (CT) of the chest annually for people who meet a set of certain criteria that put them at increased risk. Candidates for screening must meet all of these criteria:

  • Age between 50 and 80
  • 20 pack-year or more history of smoking
  • Currently smoke or quit within the past 15 years

For someone who meets all of these criteria, the USPSTF does not advise they be screened if they aren't healthy enough overall to undergo treatment if they're diagnosed with lung cancer.

The USPSTF also does not recommend using other criteria for screening, such as exposure to carcinogens other than cigarette smoke, such as radon or asbestos.

Other people who may not benefit from lung cancer screening include those with pacemakers or rods, as the metal such implants are made of can interfere with the screening process and produce low-quality results. Individuals who are not in good health, such as those on home oxygen tanks, may not be good candidates for screening either.

According to the Centers for Disease Control and Prevention, any who wants to be screened for lung cancer should first talk to their doctor to make sure it's appropriate for them. If so, the doctor can refer them to a screening facility.

Tests Used for Screening

A low-dose computerized tomography (LDCT) scan is the only recommended screening for lung cancer. It is most often performed in healthy people who have no symptoms but are at high risk of lung cancer. The scan only takes a few minutes and is not painful.

Why Chest X-Rays Are Not Good for Lung Cancer Screening


Chest X-rays
are not considered good for lung cancer screening because overlapping structures can make it difficult to parse out a tumor. Moreover, X-ray imaging cannot visualize soft tissues. An X-ray sends small doses of radiation through the body. Bones, which are high in calcium, show up clearly on X-ray because of their density and because they have a higher atomic number than most elements and can absorb the X-rays. This results in them appearing white on the screen. Soft tissues, such as those in the lungs, appear in various shades of grey on X-ray, which can be difficult to read. An X-ray may detect an unusual mass in the lungs, but it would be extremely difficult to ascertain if it is a tumor.

A CT scan also uses radiation, but captures more detail than X-ray. This is because it uses multiple x-ray images from different angles to create a 360-degree computerized image. This allows for much more detail to be captured and helps with a more accurate diagnosis of lung cancer.

Genetic testing is another tool for checking for your risk of lung cancer, but it is not considered or used as a screening test. Both specific germline and somatic mutations can increase your risk of developing lung cancer. Genetic testing for germline mutations helps to identify if you have any inherited lung cancer risks.

Most people who develop lung cancer at a younger age, commonly women and non-smokers, have a genetic predisposition to the disease. For example, EGFR T790M mutations are more commonly found in lung cancer patients who have never smoked than in patients who have smoked.

Researchers have identified other kinase-domain-associated germline mutations that predispose individuals to develop lung cancer. However, it is important to note that even without germline mutations, smokers are still at risk of lung cancer. Genetic testing to assess for cancer risk is not a replacement for cancer screening.

Procedure

During an LDCT scan, several X-ray images are taken, and a computer generates a three-dimensional model of your lungs. A contrast agent may be used to help visualize images. The procedure involves lying on a table that slides into a scanner while the scanner revolves around you, taking X-rays. Minimal discomfort is expected with an LDCT scan.

It is recommended to wear a comfortable outfit and leave any valuable jewelry at home since you will need to remove it prior to the scan.

Test Results

If the LDCT scan returns abnormal findings, a biopsy will be performed. A biopsy does not mean you have cancer. In order for an official diagnosis of lung cancer to be made, a sample of lung tissue must be taken for a closer examination under a microscope.

Benefits of Lung Cancer Screening

The main benefit of screening is a lower chance of dying from lung cancer, which accounts for many deaths in current and former smokers. For people at high risk of lung cancer, getting yearly LDCT scans before symptoms start helps lower the risk of dying from lung cancer. The mortality benefit of lung cancer screening comes from the fact that if it's caught at a very early stage, lung cancer can often be treated effectively. 

As with any type of screening, not everyone who gets screened will benefit from lung cancer screening. Screening with LDCT will not find all lung cancers, and not all of the cancers that are found will be found early.

Risks

Risks of the screening include false-positive results (suggesting that a person has lung cancer when no cancer is present) and radiation exposure, which can cause cancer in otherwise healthy people. False-positive results that led to an invasive procedure has been estimated at between 2% and 4%. Excess risk stemming from radiation exposure from LCDS has been reported as less than 1% for both men and women. The risks of a procedure should always be weighed against its benefits.

An LDCT scan of the lungs does not involve scanning of the abdomen and should involve minimal risk to those who are pregnant. If you are thinking about getting screened, talk to your doctor. If lung cancer screening is right for you, your doctor can refer you to a high-quality screening facility.

What to Do If You Test Positive?

Sometimes screening tests will show something abnormal in the lungs or nearby areas that may be cancer, but most of these abnormal findings will turn out not to be cancer. More CT scans or other tests like MRI and PET scan will be needed to be sure. 

If a diagnosis of lung cancer is confirmed, the experience may be overwhelming. During this time, it is important that you seek support from loved ones and maintain open communication with your provider to discuss treatment options. Options range from surgery to targeted therapy. For example, for patients with NCSLC, recent developments in molecular testing can help identify a tumor's subtype to personalize the treatment plan.

You may also wish to speak with other patients who have undergone or are undergoing, treatment for lung cancer. A lung cancer diagnosis is not something you need to handle alone.

A Word From Verywell

Early detection is the best protection against lung cancer. You may wish to discuss the benefits of early diagnosis with your provider. When evaluating your risk for lung cancer, it is important to consider family history, a history of smoking, relevant occupational exposures, and other factors. Reducing your risk of lung cancer can involve smoking cessation and adopting healthy lifestyle habits.

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