What Causes Lung Cancer?

Physician John Hill discovered the link between smoking and lung cancer in 1761. Smoking tobacco is the primary cause of developing lung cancer. Other factors that can increase your risk include being exposed to secondhand smoke or other toxins (e.g., radon or asbestos) and having a family history of the disease.

Lung cancer is the leading cause of cancer deaths worldwide and the third most common cancer in the United States. This disease occurs when cancerous cells begin to grow in the lungs. Lung cancer can either start in the alveoli (sacs in the lungs that help you breathe in air) or the bronchi (small tubes that carry oxygen to your lungs).

You can substantially lower your lung cancer risk by quitting smoking. It's a good idea to regularly screen for lung cancer if you used to smoke. Continuing smoking after receiving a lung cancer diagnosis may worsen your condition quickly.

Smoking 

Research has found that 80% to 90% of all people who receive a lung cancer diagnosis are those who have a long history of smoking cigarettes and other tobacco products (e.g., pipes and cigars). People who smoke are up to 30 times more likely to get lung cancer than people who don't use tobacco.

Cigarettes contain more than 7,000 toxic chemicals. These toxins can damage the lining of the lungs, weaken the immune system, and prevent your body from fighting against cancer cells. Toxins from tobacco can also change the genetic structure of your DNA. Lung cancer cells can grow out of control and create a tumor in your lungs if your DNA changes.

The abnormal growth of cancer cells starts in the lungs. Cancer cells can quickly metastasize (spread) to nearby tissue, lymph nodes, the blood, and other major organs. 

Secondhand Smoke

Exposure to secondhand smoke, or smoke from someone else's cigarettes, can increase your risk of lung cancer. More than 7,000 lung cancer deaths each year are people who develop lung cancer due to secondhand smoke.

Inhaling secondhand smoke is not something you can always control. Some ways to avoid exposure to secondhand smoke are to stay away from indoor public places that still allow smoking, move away from people in public who are smoking cigarettes, and ask people not to smoke in their homes or cars. 

Exposure to Toxins

People with lung cancer can develop the disease because of exposure to environmental toxins. Exposure to these chemicals may increase your risk:

• Asbestos: This group of minerals is made of heat-resistant materials. Asbestos was used for a variety of things: building homes and cars, insulating hot water pipes, and making paint and plastics. The Environmental Protection Agency (EPA) banned the use of asbestos in 1989 due to its increased risk of health hazards, including lung cancer. The use of asbestos has significantly declined since the EPA ruling. Asbestos may still be present in older buildings, pipes, and products.
• Radon: This is the second leading cause of lung cancer. Radon is a naturally occurring radioactive gas found in rocks and soil. Most radon exposure happens indoors in places like homes, schools, and workplaces. Radon is colorless and odorless, which makes it especially difficult to detect inside. A professional can test if you have radon at home and install a ventilation system to reduce radon levels. You can also test your radon levels for free using at-home test kits that your local or state government office may provide.

Arsenic, chromium, and nickel are metals that may also increase your risk of lung cancer. Arsenic is found in soil, groundwater, and seafood. Chromium is found in rocks, plants, and paints. Nickel is found in batteries and cars.

Is Lung Cancer Hereditary? 

Genetics can play a role in lung cancer risk. You may be more likely to develop the disease if a family member has or has had lung cancer.

There are two main types of lung cancer: non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Having a family history of lung cancer can increase your risk of SCLC. A study published in 2021 found that you can inherit certain genetic changes (mutations) that cause cancer cells to develop and grow out of control.

Who Gets Lung Cancer?

Some people may be more likely to develop lung cancer than others. Certain demographic factors that can increase your risk include:

• Age: Most people who receive a lung cancer diagnosis are older than 65.
• Ethnicity: Black men are more likely to get lung cancer than White men. Racial disparities in healthcare also reduce the likelihood of Black people receiving surgical treatment options for lung cancer, which increases their risk of dying from lung cancer.
• Geographic location: Some evidence suggests that people living in rural areas may be more likely to develop lung cancer due to higher levels of tobacco use.
• Sex: People assigned male at birth have a slightly higher risk of developing lung cancer than people assigned female at birth. Lung cancer is the second most common cancer in both males and females.

A Quick Review

Lung cancer is one of the most common cancers you can develop and also the most deadly. It can be scary to get tested for this disease. Knowing the causes of lung cancer may help you reduce your risk.

Smoking cigarettes is the leading cause of lung cancer. You can also get lung cancer from secondhand smoke, exposure to toxic chemicals like radon and asbestos, or a family history of lung cancer. 

Quitting smoking and getting screened regularly for the disease, especially if you're at an increased risk, can help get you an early diagnosis. Finding out about your lung cancer diagnosis in an early stage can help you get started on treatment sooner and improve disease progression down the road.