When a person receives a lung cancer diagnosis, their family members may worry about also being at risk of the condition. In some families, genetic factors that increase the risk of cancer are passed down through generations. However, inherited genes are seldom the main cause of lung cancer.

Environmental or lifestyle factors also affect a person’s chances of developing lung cancer. Sometimes, they may affect several family members, without a genetic cause. Although a person can’t change their genes, they can control other factors that may help decrease lung cancer risk.

Inherited vs. Acquired Gene Mutations

Like other cancers, lung cancer is caused by gene mutations (changes) that allow cells to grow and divide in a disorganized way. Anything that increases a person’s risk of developing genetic mutations can also increase their risk of lung cancer.

There are two main types of genetic mutations — inherited and acquired.

Inherited mutations:

• Are passed down from parent to child
• Are found in every cell within the body, starting at birth
• Can sometimes lead to hereditary cancers that run in families

Acquired mutations:

• Develop throughout a person’s life
• Occur in just one or a few cells
• Are caused by environmental or lifestyle factors that damage a cell’s DNA

Hereditary Lung Cancers

People with a family history of lung cancer — including a parent, child, or sibling diagnosed with this condition — are more likely to develop cancer themselves. However, lung cancer may run in families due to either genetic factors or shared environmental factors. It’s not often possible to know which factors caused the disease.

Lung cancer is usually not hereditary. Only about 8 percent of lung cancer cases are caused by inherited “lung cancer genes.” It’s not always clear what these mutations are. Inherited genetic changes may affect how cells grow and divide, raising the risk of certain cancers.

Family Cancer Syndromes

Sometimes, multiple cases of cancer occur within a family due to a single inherited gene change. This leads to family cancer syndromes, in which multiple family members develop the same types of cancer, often at a young age. Family cancer syndromes can also cause one person to develop more than one type of cancer.

Some family cancer syndromes can lead to an increased risk of lung cancer. For example, Li-Fraumeni syndrome is caused by an inherited mutation in the TP53 gene. This condition can also raise a person’s chances of developing breast cancer, leukemia, or soft tissue sarcoma (cancer that develops in muscle, nerve, blood vessel, bone, or fat tissue).

Hereditary breast and ovarian cancer syndrome primarily leads to cancer in the breasts and ovaries. It’s caused by mutations in the BRCA1 or BRCA2 genes. People with these inherited mutations have a greater chance of being diagnosed with liver cancer or laryngeal cancer.

Peutz-Jeghers syndrome is caused by an inherited mutation in a gene called STK11. Peutz-Jeghers syndrome can lead to lung cancer in addition to breast, ovarian, cervical, uterine, pancreatic, and colon cancers.

Environmental Causes of Lung Cancer in Families

Lung cancer is usually caused by environmental or lifestyle factors that damage genes during a person’s life. These factors lead to acquired gene mutations that may turn normal lung cells into cancer cells.

Smoking is the leading cause of lung cancer. About 80 percent of lung cancer deaths are caused by smoking. People who don’t smoke are also at higher risk when exposed to secondhand smoke. The more a person smokes and the longer they smoke, the higher their risk will be. Additionally, inhaling secondhand tobacco smoke can somewhat increase lung cancer risk and is responsible for many cancer deaths.

Another large environmental risk factor is air pollution. Factories sometimes release cancer-causing substances in the air. Diesel exhaust also contains chemicals that can damage the lungs and lead to cancer.

Exposure to certain chemicals can also increase lung cancer risk. Possible cancer-causing chemicals include:

• Radon — A radioactive gas that may be found in the basements of certain homes or buildings
• Asbestos — A substance that was often previously used in building materials, car parts, and textiles
• Diesel exhaust — Air emitted by engines that run on diesel gasoline
• Certain chemicals that may be used in the workplace — Arsenic, silica, chromium compounds, vinyl chloride, coal, and mustard gas

Even when lung cancer develops in multiple people within the same family, it may be caused by lifestyle rather than genetic factors. Family members often share environmental factors. For example, many people within the same family may smoke or live in an area with a lot of pollution. If you have one or more family members with lung cancer, following steps to avoid environmental risk factors can help you decrease your chances of being diagnosed with this condition.

Can Lung Cancer Be Prevented?

It’s not possible to completely prevent lung cancer. Some people with this condition have never smoked and have no other known risk factors, so it’s not always clear what causes this cancer. However, many risk factors are known and can be minimized.

The best way to protect against lung cancer is to quit smoking or never start in the first place. The American Cancer Society, American Lung Association, and Centers for Disease Control and Prevention (CDC) all offer programs and resources that can help you stop using cigarettes.

Quitting smoking now will have a big impact on your future risk. For example:

• If you have a history of heavy smoking and then quit, you’ll have a 39 percent lower risk of lung cancer five years later. Your risk will continue to drop over time.
• If you quit smoking before you turn 40, you’re 90 percent less likely to die from lung cancer or another condition caused by smoking. If you quit before turning 54, you’re two-thirds less likely to die from these illnesses.
• If you have just been diagnosed with cancer and currently smoke, quitting now makes you up to 40 percent less likely to die from cancer.

In addition to quitting smoking, you can control other environmental and lifestyle factors that lead to a high risk of lung cancer. Take steps like these to minimize risk:

• Test your home to see if any radon gas is present. If there is, treat your home to avoid exposure.
• If you work with carcinogens (cancer-causing chemicals), limit how much you’re exposed to them. Wear personal protective equipment and follow safety guidelines when working with these substances.
• Eat a balanced diet containing plenty of fruits and vegetables.
• If you smoke, avoid vitamins or supplements that contain beta-carotene, as it can increase lung cancer risk.

If you have a history of smoking, undergo lung cancer screening each year starting at age 50. During screening, doctors use CT scans to look inside your lungs. Screening may help catch lung cancer early, when it’s more treatable.

Additionally, familiarize yourself with the symptoms of lung cancer. Let your doctor know if you’re experiencing:

• Ongoing coughing
• Coughing up blood
• Frequent chest infections
• Shortness of breath
• Chest pain
• Tiredness

If you’re worried that you or your family members will develop lung cancer, talk to your doctor. They can help you understand your risk factors and tell you more about reducing cancer risk. You may also be able to talk to a genetic counselor, who can perform genetic testing to look for gene mutations that can increase lung cancer risk.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Do you have a family history of lung cancer? Have you taken steps to reduce your risk? Share your experience in the comments below, or start a conversation by posting on your Activities page.