Lung Cancer and Genetics
A build-up of genetic changes can lead to lung cancer. This can happen when changes occur in the genes that support cell growth, division, and survival (oncogenes) or in the genes that dictate cell division and death (tumor suppressor genes).8
In non-small cell lung cancer cases, for example, mutations in EGFR or ALK genes often occur in the adenocarcinomas of non-smokers, while KRASmutations are associated with smokers and former smokers.9
Patients typically acquire the genetic changes related to lung cancer during life. Experts have documented lifestyle and environmental factors that increase the risk of genetic mutations, like cigarette smoke and air pollution.7 But the root causes of some changes remain unclear.8
Inherited genetic changes—which come from a person’s parents—can increase the risk of lung cancer,8 but inherited mutations are not associated with many lung cancer cases. Moreover, the increased risk may stem from shared risk factors rather than inherited genetic changes.7
Some lung cancers are linked to acquired genetic changes with abnormalities in DNA.7 The causes of these acquired abnormalities are unclear, but they may be associated with certain risk factors. For example, a mutation in the KRAS gene is present in about 20% to 25% of non–small cell lung cancers (NSCLCs). This gene change enables the cancer cells to grow and spread and can affect the disease and treatment options. Approximately 5% of NSCLCs have a change in the ALK gene, which is more often seen in non-smokers and light smokers. Other examples include NSCLCs that have a rearrangement in the ROS1 gene. seen in 1% to 2% of cases, or changes in the BRAF gene, detected in about 5% of cases.9
Lung Cancer Risk Factors
Not everyone who develops lung cancer smokes, and not everyone who smokes develops lung cancer. Lung cancer in nonsmokers and smokers may result from a combination of risk factors.8 Other risk factors for NSCLC, in particular, include:10
- Asbestos. This material was often used as insulation in buildings, and people may be exposed through their jobs.
- Radon. Some rocks and soil release this odorless gas.
- Air pollution. People exposed to outdoor air pollution from factories, cars, fires, and other sources have a higher risk for lung cancer.
Lung Cancer Prevention
Not smoking is the best way to avoid lung cancer. Avoiding secondhand smoke is also key to prevention.11
Environmental exposures through work or in the home increase the risk of developing cancer. Wearing a respirator and other protective gear when working with asbestos or other cancer-causing agents can help reduce the risk of developing NSCLC. A radon detector can let you know when high levels of radon are present, and then you can take steps to reduce radon leaks.10
Metastatic Lung Cancer
Cancer can spread beyond the original tumor when the tumor sheds cancer cells. These cells enter the bloodstream or lymph nodes, where they can then spread to other parts of the body.12
Cancer is named by the original location of the tumor.12 If lung cancer spreads to another area of the body, it is called metastatic lung cancer.13,14
Lung cancer most often spreads to:13
- Nearby lymph nodes or other parts of the lung and chest
- Adrenal glands
Other types of cancer can also spread to the lungs. Those cancers are still named after the original site of the tumor. For example, breast cancer that spreads to the lungs is called metastatic breast cancer.12 Cancers that most commonly spread to the lungs include:14
- Head and neck