Basic overview of lung cancer: Risk factors, cancer types, and screening

February 28, 2023

What is cancer?

Cancer is a disease in which the abnormal cells in one’s body grow in an uncontrolled way. They may eventually spread to other parts of the body. When the cancer starts invading nearby tissues and spreading to other organs, the process is called metastasis. According to American Cancer Society,  more than 1.9M new cancer cases and 609,820 cancer deaths are expected to occur in the United States in 2023.

What is lung cancer?

Lung cancer is the third most common cancer in the U.S. after breast and prostate cancer. As the name suggests, lung cancer is the type of cancer that starts in the lungs (usually in the bronchi or alveoli). When damaged cells in lungs divide uncontrollably, they may inhibit the lungs from functioning normally. American Cancer Society estimates that about 238,340 new cases of lung cancer will be detected in 2023. Lung cancer is currently the leading cause of cancer death in the US, with more than 127,070 deaths estimated this year.

Structure and parts of the lungs. Bronchial tree, main stem bronchus, bronchioles, bronchi, alveoli.

Structure and parts of the lungs. Bronchial tree, main stem bronchus, bronchioles, bronchi, alveoli.

What are the main risk factors for lung cancer?

Most people diagnosed with lung cancer are 65 or older. Some of the risk factors for lung cancer are:

  • Smoking
  • Exposure to asbestos
  • Secondhand smoke
  • Exposure to radon
  • Exposure to carcinogens (cancer-causing agents) at workplaces
  • Arsenic in drinking water
  • Air pollution
  • Personal or family history of lung cancer

However, having one or several risk factors does not mean that you will get lung cancer. These risk factors could make you more likely to develop the disease.

For more information on the risk factors, please visit American Cancer Society.


Did You Know?

In the United States, about 10% to 20% (20,000 to 40,000 cases) of lung cancer cases happen in people who never smoked or smoked fewer than 100 cigarettes in their lifetime.


What are the different types of lung cancer?

Lung cancer can be classified into two main types: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

Non-small cell lung cancer (NSCLC)

NSCLC is the most common type of lung cancer. About 80% to 85% of lung cancers are NSCLC. While they are less aggressive when compared to SCLC, it is important to detect NSCLC early so that it does not spread to nearby tissues. NSCLC can be further divided into subtypes like adenocarcinoma, squamous cell carcinoma and large cell carcinoma.

Small cell lung cancer (SCLC)

SCLC is more aggressive than NSCLC and can quickly metastasize to neighboring tissues. In most people, SCLC is diagnosed after it has already spread beyond the lungs.

The healthcare professional would be able to identify the type of lung cancer when they take a biopsy and send it to lab for examination.

What are the symptoms of lung cancer?

Different people exhibit different lung cancer symptoms. It is important to note that most people with lung cancer do not have symptoms until later stages. Some of lung cancer symptoms may include:

  • A cough that does not go away or gets worse
  • Shortness of breath
  • Coughing up blood
  • Chest pain that may worsen with deep breathing, coughing or laughing
  • Feeling weak or tired
  • Wheezing
  • Unexplained weight loss

These symptoms are not specific to lung cancer and can be caused by other illnesses as well. If you have any of these symptoms, please talk to your healthcare provider so that they can find the cause.

Screening for lung cancer

The U.S. Preventive Services Task Force (USPSTF) recommends annual screening for lung cancer with low-dose computed tomography (low-dose CT or LDCT) for people who:

  • Are between 50 to 80 years old, and
  • Have 20 pack-year smoking history*, and
  • Currently smoke or have quit within the past 15 years.

*A pack-year is equal to smoking an average of one pack of cigarettes per day for one year.

Cancer screening with low-dose CT

A low-dose CT scan is a special type of X-ray that gives off low dose of radiation to take multiple pictures as the patient lies on a table. The table slides in and out of a machine which takes pictures from different angles to create a 3-D view of the lungs. Physicians can then identify nodules or other abnormal features in the lungs.

Risks of screening for lung cancer with low-dose CT

While there has been a significant reduction in lung cancer mortality with LDCT screens, the screening technique comes with a few risks. Some of the risks of lung cancer screening are:

  • Lung cancer screening tests may result in false-positive results. This means that the tests could suggest that a person has lung cancer even if there is no cancer present. This could result in unnecessary invasive diagnostic procedures.
  • Lung cancer screening tests may find cancer cases that may have never caused a problem for the patient. This overdiagnosis may lead to unnecessary treatments.
  • Repeated LDCT tests can increase exposure to radiation that can cause cancer.

Because of these concerns, regular screening is limited to individuals who meet the high-risk criteria as mentioned above.

Insurance and Medicare Coverage

Many insurance plans and Medicare may help pay for recommended lung cancer screening tests. Check with your insurance plan to find out what benefits are covered for lung cancer screening. For more information about Medicare coverage, visit or call 1-800-MEDICARE (1-800-633-4227). TTY users can call 1 (877) 486-2048.