When a person receives a lung cancer diagnosis, their family members may worry they’re also at risk for developing the condition. In some families, genetic factors that increase the risk of cancer are passed down through generations.

There are also environmental or lifestyle factors that 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.

Lung Cancer and Gene Changes

Like other cancers, lung cancer is caused by gene mutations (changes) that allow cells to divide and grow 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 gene mutations. It’s not always clear what these mutations are. Inherited genetic changes may make it harder for cells to remove toxic substances or heal damage.

Family Cancer Syndromes

Sometimes, many 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 multiple types 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 sarcomas (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 is 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 cancer, ovarian cancer, cervical cancer, uterine cancer, pancreatic cancer, and colon cancer.

Environmental Causes of Lung Cancer

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 85 percent of lung cancers are caused by cigarette 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. Additionally, diesel exhaust 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. People within the same family 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 lung cancer risk factors are known and can be minimized.

The best way to protect against lung cancer is to quit smoking or to never start smoking 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:

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

• Test your home to see if there is any radon gas present. If there is, treat your home to avoid exposure.
• If you work with carcinogens (cancer-causing chemicals), limit how much you are exposed to them. Wear personal protective equipment and follow safety guidelines when working with these substances.
• Eat a balanced diet containing large amounts 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 a computed tomography (CT) imaging test to look inside your lungs. Screening may help catch lung cancer early, when it is more treatable. Additionally, familiarize yourself with the symptoms of lung cancer. Let your doctor know if you are experiencing:

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

If you are 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 5,200 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? Share your experience in the comments below, or start a conversation by posting on your Activities page.