Lung cancer, like other types of cancer, occurs due to genetic mutations (variations or changes) that cause cells to grow and divide uncontrollably. Factors that increase the risk of developing these mutations also raise the risk of lung cancer.

This article will explore various causes of lung cancer, the role of genetic mutations, and how different risk factors contribute to this disease. Understanding these causes may help you reduce your risk and be better informed when discussing prevention and treatment with your health care provider.

Genetic Mutations and Lung Cancer

Genetic mutations are changes in your DNA that can influence how cells grow and function. In lung cancer, there are two types of mutations to be aware of: inherited and acquired.

Inherited mutations:

• Are passed down through family, from parents to children
• Are present in the DNA of all cells at birth
• Occur less often than acquired mutations

Acquired mutations:

• Accumulate throughout your life
• Are present in the DNA of only some cells
• Are caused by aging and exposure to carcinogens (cancer-causing agents), such as cigarette smoke, chemicals, radiation, and more

While lung cancer can run in families, it is usually linked to acquired mutations caused by external factors. However, it’s still unclear why some people develop lung cancer and others don’t, even when exposed to the same risks.

Acquired Mutations Associated With Lung Cancer

Certain acquired genetic mutations play important roles in the development of lung cancer. For example, changes in the RB1 gene, which normally helps control cell growth, are often linked to small cell lung cancer (SCLC). Mutations in other genes, like p16 and KRAS, are more commonly found in non-small cell lung cancer (NSCLC).

Every case of lung cancer is unique, and new mutations are still being discovered. These genetic changes can help guide personalized treatments, making it possible to target specific mutations with therapies designed to stop or slow cancer growth.

How Cells Transform Into Cancer

Normal cells divide in a regular, ordered fashion, creating new cells that are exact copies to replace old ones. Certain genes are responsible for telling cells when to divide and when to stop. Other genes and proteins search for errors in DNA and fix them when DNA is not copied correctly. If an error is found that cannot be fixed, the cell will self-destruct.

If a genetic mutation turns certain genes on or off, then cells can divide at a faster rate without regulation or order. In turn, this allows more and more mutations to accumulate, speeding the unchecked growth of abnormal cells. Eventually, these abnormal cells will form a tumor and become cancerous.

Risk Factors for Lung Cancer

It’s important to understand that although science can find links between factors and diseases, those links don’t always mean that one factor directly causes the disease. Many risk factors for lung cancer have been identified and are being studied for their role in the development of the disease.

Because genetic mutations cause lung cancer, risk factors for lung cancer include anything that can encourage these mutations. It is also important to note that risk factors may vary by the type of lung cancer.

Age

Mutations in DNA are inevitable, and they accumulate with age. In rapidly dividing tissues, researchers estimate that tens of thousands of mutations may accumulate by age 60. However, cancer only develops in a small percentage of people.

For most cases of lung cancer, risk increases with age. Most people are diagnosed with lung cancer at age 65 or older. The average age of diagnosis with lung cancer is around 70 years old. A very small number of people are diagnosed under the age of 45.

Inherited Risk Factors for Lung Cancer

If you have a family history of lung cancer, you are at an increased risk of developing it yourself. Having siblings or parents who had lung cancer may slightly increase your risk, particularly if they were diagnosed at a younger age. It’s also possible that you may share exposure to environmental risk factors with them, such as radon or secondhand tobacco smoke. Overall, approximately 8 percent of lung cancer cases are inherited or due to genetic predisposition.

In some cases of lung cancer, people may inherit faulty genes or mutations from their parents. People who inherit certain mutations found on chromosome 6 are more likely to develop lung cancer, regardless of their smoking status. Usually, these few inherited mutations are not enough to cause many lung cancers.

Because cancer is an age-related disease, it’s thought that lung cancer in younger people may be due to inherited factors. Some people may inherit faulty DNA-repair mechanisms or a reduced ability to break down carcinogens. All of these factors can contribute to an increased risk of lung cancer.

Sex and Race/Ethnicity

Recent statistics from the American Lung Association reveal important differences in how race/ethnicity and sex influence lung cancer incidence and outcomes. These data highlight disparities in both diagnosis and death rates across various demographic groups.

According to the American Lung Association, in 2019, men were 23 percent more likely to be diagnosed with lung cancer than women, with incidence rates of 59.2 per 100,000 for men and 48.1 per 100,000 for women. The rate of new lung cancer cases was higher among men than women across all racial and ethnic groups.

From 2016 to 2020, Black males had the highest incidence rate (68.3 per 100,000), followed by white males (61.5 per 100,000). Rates were lower among Asian/Pacific Islander males, American Indian/Alaska Native males, and lowest among Latino males.

Among females during the same period, white females had the highest incidence rate (52.7 per 100,000), followed by American Indian/Alaska Native females (44.4 per 100,000) and Black females (44.0 per 100,000). Rates were much lower among Asian/Pacific Islander females and lowest among Latina females.

Lung cancer death rates also show disparities. From 2016 to 2020, Black males had the highest death rate (51.0 per 100,000), followed by white males (44.7 per 100,000) and American Indian/Alaska Native males (39.9 per 100,000). Death rates were much lower among Asian/Pacific Islander males and lowest among Latino males.

For females, white females had the highest death rate (32.8 per 100,000), followed by American Indian/Alaska Native females (29.9 per 100,000) and Black females (27.8 per 100,000). Death rates were much lower among Asian/Pacific Islander females and lowest among Latina females.

A mutation in the epidermal growth factor receptor (EGFR) protein is associated with NSCLC adenocarcinoma cases in young Asian women who do not smoke.

Environmental Factors for Lung Cancer

Environmental factors play a large role in the risk of developing lung cancer because the air you breathe can bring chemicals, pollution, and other irritants into the lungs. Continued exposure to these risk factors may increase your chances of developing lung cancer.

Smoking

Some people who smoke all their lives never develop lung cancer, while some who smoke rarely or not at all may develop it. However, the leading risk factor for lung cancer is smoking, and smoking accounts for around 80 percent of lung cancer deaths. Smoking is a major risk factor for SCLC in particular, which is rarely diagnosed in people who don’t smoke.

The method of smoking does not seem to affect the risk of developing lung cancer — cigarettes, cigars, and pipes all contribute to the increased risk. Tobacco smoke contains at least 70 known carcinogens that damage lung cells and lead to cancer. Therefore, exposure to secondhand smoke may also increase your risk of lung cancer.

Vaping and e-cigarettes are newer forms of smoking, and no studies are available on their long-term effects. However, many chemicals in vapes are known to cause cancer, which is why researchers think vaping could raise the risk of lung cancer, though more research is needed. Breathing in secondhand e-cigarette vapor may also carry risks.

Air Pollution

Air pollution seems to slightly increase the risk of lung cancer. This can be true in cities with high levels of air pollution, especially near busy roads. However, it appears to be far less of a risk compared to smoking. About 5 percent of all lung cancer deaths may be caused by outdoor air pollution.

Radon

Radon is a radioactive gas that naturally forms when uranium found in rocks and soil breaks down. It is invisible and has no smell or taste. According to the Environmental Protection Agency (EPA), radon is the second leading cause of lung cancer behind smoking. It’s also the leading cause of lung cancer in people who don’t smoke.

Radon gas can be found in buildings in nearly any part of the United States, especially in basements. Breathing in radon exposes your lungs to microdoses of radiation, increasing your risk of developing lung cancer.

Asbestos

Asbestos is a fibrous material that was commonly used as insulation in older buildings. If asbestos fibers are inhaled or ingested, they can become permanently trapped in the body. This can cause inflammation and irritate the lungs, eventually leading to cancer.

People who work with asbestos and are exposed to large amounts of it have a greater risk of developing mesothelioma, a form of cancer that originates in the lining around the lungs, called pleura. Asbestos can be found in many workplaces, such as mills, mines, textile plants, and shipyards. Furthermore, the lung cancer risk is much greater in workers exposed to asbestos who also smoke. Most cases of lung cancer occur at least 15 years after the first exposure to asbestos.

Chemicals in the Workplace

Here are some other carcinogens found in some workplaces that can increase the risk of lung cancer:

• Diesel exhaust
• Radioactive ores, such as uranium
• Inhaled chemicals, such as cadmium, arsenic, nickel compounds, coal products, chromium compounds, and mustard gas

Recently, there has been more awareness around protecting workers from harmful chemicals, but any exposure may still put you at risk. Always use protective equipment and limit your exposure to carcinogenic materials whenever possible.

Dietary Supplements

While they may appear beneficial, some vitamins and dietary supplements can actually increase the risk of lung cancer. Two large studies found that people who smoked and took beta-carotene supplements had an increased risk of developing lung cancer. According to the American Heart Association, these findings suggest people should avoid taking beta-carotene supplements.

Radiation Treatment for Cancer

Radiation therapy is a useful cancer treatment that damages cancer cells beyond repair, causing them to stop growing or die. Unfortunately, radiation can also damage healthy cells in the body, increasing the risk of cancer.

People who have had radiation therapy to the chest to treat other types of cancer are at a higher risk of developing lung cancer, especially if they smoke. This might include individuals who have been treated with chest radiation for breast cancer and people who have been treated for Hodgkin lymphoma. However, individuals who receive radiation therapy following a lumpectomy on the breast do not appear to have a higher risk of lung cancer.

Can Lung Cancer Be Prevented?

There’s no sure way to prevent lung cancer, but you can lower your chances. While risk factors such as family history and previous cancer treatment can’t be changed, there are lifestyle and environmental factors that may be within your control.

If you’re concerned that you may be at a higher risk of developing lung cancer, here are some measures you can take to lower your risk:

• Stop smoking and avoid exposure to secondhand smoke.
• Take precautions when working with carcinogenic chemicals or radiation to limit your exposure. Use protective equipment at all times and follow posted safety procedures.
• Avoid taking any dietary supplements that may increase your risk of developing lung cancer.
• Eat a healthy diet with plenty of fresh fruits, vegetables, and whole grains, while limiting your intake of processed meats.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 13,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

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