Although environmental and lifestyle factors often cause lung cancer, sometimes the disease can be genetic. Some genetic mutations that contribute to lung cancer run in families, but others do not.
According to the World Health Organization (WHO), lung cancer was the second most common cancer worldwide in 2020. It caused 1.8 million deaths that year, making it the leading cause of cancer-related death.
Both genetic and environmental factors can cause lung cancer. However, smoking remains the leading cause of lung cancer and accounts for around 80–90% of cases.
Some experts estimate that a genetic predisposition to lung cancer accounts for around 8% of cases. Some of these genetic risk factors are inherited, which means they run in families.
However, other genetic changes are not inherited. A person’s genes can mutate due to environmental factors such as smoking and pollution.
Smoking is the leading cause of lung cancer. Secondhand smoke can also increase a person’s risk of developing lung cancer.
People who smoke and also encounter environmental risk factors such as radon are at an even higher risk.
Other factors that can contribute to a person’s risk of lung cancer include:
- Radon exposure: This radioactive gas occurs naturally in the environment and because it is colorless and odorless, it can go undetected. Approximately 1 in 15 households in the United States are exposed to radon.
- Hazardous chemicals: People who work with asbestos, uranium, cadmium, arsenic or various petroleum products have an increased risk of lung cancer.
- Particle load: Particles from exhaust smoke, dust and other sources enter the air and can increase the risk of lung cancer.
- Genetic factors: People with certain genetic factors may be at increased risk.
In some cases, gene mutations that contribute to lung cancer can be hereditary, meaning a person is more likely to develop the disease after it affects a close relative.
A 2011 study suggests that a person’s genes are more likely to contribute to an increased risk of lung cancer when they’re young and have never smoked.
However, lung cancer can also run in families due to shared environmental factors and lifestyle habits. For example, families can live in an area with high levels of hazardous chemicals.
Smoking can also affect family members. Research has shown that children who live with people who smoke are more likely to smoke. In addition, living with someone who smokes exposes children to harmful chemicals.
Research suggests that both genetic and environmental factors influence a person’s risk of lung cancer. However, doctors do not fully understand the genetic factors responsible for lung cancer.
Individuals can inherit genetic mutations from their biological parents that increase their risk of developing lung cancer. They can also acquire genetic mutations later in life when exposed to toxins, chemicals, or other environmental factors.
Inherited genetic changes
Some genetic factors are inherited. Researchers know that changes in DNA in a particular chromosome, such as chromosome 6, can affect a person’s risk of lung cancer in a number of ways.
Some people can inherit genes that make them less able to break down the cancer-causing chemicals in tobacco smoke. Others can inherit an inability to repair their DNA, making them particularly vulnerable to radiation and cancer-causing chemicals.
Some cases of lung cancer occur because of a mutation in the epidermal growth factor receptor (EGFR). EGFR helps cells grow, and a mutation that affects it can cause cells to run out of control and cause cancer.
EGFR mutations are responsible for about 32% of non-small cell lung cancers worldwide. Non-small cell lung cancer is the most common type of lung cancer, accounting for 80–85% of all lung cancers.
Among non-smokers, this gene mutation is most common in women in East Asia.
Acquired genetic changes
An individual usually acquires the genetic changes that cause lung cancer rather than inheriting them.
People can get gene mutations from multiple sources. Exposure to certain environmental toxins can change the way cells grow, divide, and die.
However, some genetic changes are not due to an external cause and occur randomly.
Acquired genetic changes can influence tumor suppressor genes. If these don’t work properly, they won’t stop abnormal cells from growing. Some tumor suppressor genes that can cause lung cancer are:
- p16 tumor suppressor genes
- RB1 tumor suppressor genes
- TP53 tumor suppression gene
Researchers are continuing to investigate which genetic mutations cause lung cancer.
Doctors can use genetic tests to diagnose and treat lung cancer. Genetic testing involves looking for specific biomarkers or changes in genes that give the doctor more information about a person’s lung cancer.
To do genetic testing, the doctor takes a sample of the tumor and sends it to a laboratory, where technicians examine the tumor tissue for abnormal DNA.
Additionally, the doctor can look for specific mutations that indicate which treatment is best. The person can then have targeted treatment that may be more effective.
Doctors can also use a blood test to identify biomarkers that will guide their treatment decisions.
Learn more about the role of genetic testing in treating lung cancer.
A person can take steps to reduce their risk of developing lung cancer. These include:
Avoid tobacco smoke
Quitting smoking and avoiding secondhand smoke can reduce a person’s risk of lung cancer. Even if someone has smoked for years, quitting smoking can reduce the risk of developing lung cancer. It’s never too late to stop.
Learn more about smoking cessation support.
Reduce exposure to radon
Radon gas is a leading cause of lung cancer. People can reduce their exposure by testing radon levels in their home. Certain jobs, such as working in underground mines, can increase the risk of exposure to radon.
Find out more about radon exposure.
People should take precautions to protect themselves from toxic chemicals in the workplace. For example, they should wear face masks, eye protection, and other protective clothing recommended by their employer.
Learn more about avoiding carcinogens.
Lung cancer is one of the most common types of cancer, and both environmental and genetic factors can play a role in its development.
If a person has a family history of lung cancer, they are more likely to get the disease. This increased risk may be due to genetic mutations or shared lifestyle and environmental factors such as smoking and exposure to carcinogens.
An individual can inherit or acquire genetic mutations due to exposure to environmental toxins. Sometimes genetic changes have no trigger and appear randomly. Scientists still do not fully understand the genetic factors that cause lung cancer.