What we know about genetics, environmental factors and lung cancer

Environmental and genetic factors can contribute to lung cancer, which develops as a result of the cells in the lungs growing out of control.

Lung cancer is the second most common cancer and the leading cause of cancer death worldwide.

In recent years, the search for genetic mutations in cancerous lung tumors has become a crucial step in the diagnosis and treatment of lung cancer.

Experts who study the genetic mutations involved in lung cancer note that environmental and hereditary risk factors play a role.

According to Centers for Disease Control and Prevention (CDC), smoking is the number one risk factor for lung cancer.

In the United States, only 10-20% lung cancer affects non-smokers or people who have smoked less than 100 cigarettes in their lifetime. Research suggests that second-hand smoke causes more than 7,300 lung cancer deaths among non-smokers each year in the United States

the Environmental Protection Agency (EPA) estimates that radon, the second leading cause of lung cancer, kills approximately 21,000 people each year, of which approximately 2,900 have never smoked.

Other environmental factors associated with lung cancer include exposure to:

  • indoor and outdoor air pollution
  • asbestos
  • heavy metals
  • industrial emissions
  • pesticides
  • radiation therapy to the chest

Inherited DNA mutations increase the risk of certain types of cancer and may play a role in lung cancer.

The most common form of lung cancer in non-smokers is adenocarcinoma, which researchers have linked ALK and EGFR mutations. For example, in a 2017 study, the rates of ALK and EGFR mutations were higher in participants who had never smoked than in current smokers.

the American Cancer Society (ACS) notes that people who inherit certain DNA changes from chromosome 6 are more likely to develop lung cancer. Others may inherit dysfunctional DNA repair mechanisms or a reduced ability to remove carcinogenic chemicals they ingest.

The ACS explains that experts don’t believe that inherited genetic mutations alone cause many lung cancers. Genetic mutations that play a role in lung cancer are more likely to be those that people acquire during their lifetime.

Dr Osita Onugha is a thoracic surgeon and assistant professor of thoracic surgery at the Saint John’s Cancer Institute at Providence Saint John’s Health Center in Santa Monica, California.

“Genetics play a role, but we don’t know exactly what kind of role at this point,” Dr Onugha said. Medical News Today.

“We don’t have genetic testing [of healthy individuals] as is the case, for example, with breast cancer. For a patient with BRCA mutations, we know there is an increased risk of breast cancer and other cancers. We do not have the same corollary with lung cancer and hereditary genetic mutations, ”he continued.

“That’s what we know right now. Ten years from now we can say that a certain mutation means you have a particular risk of lung cancer, ”said Dr Onugha.

“There is a combination of environmental and occupational exposure and genetics. This is why some heavy smokers do not have lung cancer, and others who smoke a little do, ”he concluded.

Dr John Maurice is a thoracic surgeon and lung cancer specialist with the Center for Cancer Prevention and Treatment at Providence St. Joseph Hospital in California.

“There is definitely one trait of familial lung cancer that we have not yet scrutinized enough to understand these genes,” said Dr Maurice. MNT.

“A person with lung cancer having a relative with lung cancer is quite common. Sometimes you can identify something in it. There is a weakness in the gene repair mechanism, or the gene has a characteristic that facilitates mutations over others with a more robust repair mechanism, ”he said.

“We don’t really understand how all of the factors combine to produce cancer,” added Dr Maurice.

Second-hand smoke is a known risk factor. Dr Onugha explained that the problem is that there is no way to quantify a person’s exposure to secondhand smoke.

There may also be a link between the occupational exposure of parents or caregivers and the risk of lung cancer in children, as a review article in Translational research in lung cancer discuss. However, the exact roles of various genetic, environmental and occupational exposures in an individual are difficult to determine.

According to ACS:

  • 20 to 25% of non-small lung cancers (NSCLC) involve changes in the KRAS uncomfortable
  • 10 to 20% involve the EGFR uncomfortable
  • 5% involve the ALK uncomfortable

Other biomarkers associated with lung cancer include:

Research from 2020 found that EGFR mutations are more common in non-smokers with lung cancer than in smokers with the disease. Other common genetic mutations in non-smokers with NSCLC are ALK and KRAS.

The authors of a 2017 retrospective study concluded that lung cancer in non-smokers is under-studied. They also noted that the prevalence of lung cancer among non-smokers has increased.

“We started to detect the first genetic abnormalities associated with lung cancer about 15 years ago with EGFR mutations, ”said Dr Maurice. “Every person and every tumor has a different set of mutations, and they sometimes change over time.”

Dr Onugha explained that discussions among experts on cancer and genetics usually refer to factors that cause certain family patterns.

“In lung cancer, we usually talk about tumor biology. We call these tumor mutations biomarkers. They are not hereditary. Biomarkers tell us how aggressive a tumor is and whether it can be treated with a particular drug, ”he explained.

“Smokers and non-smokers can have different mutations. Treatment is now personalized based on the biology of your tumor, ”noted Dr. Onugha.

“We are talking about an area that has been unleashed with developments,” Dr Maurice said.

“Before, gene sequencing took a long time. You can now verify thousands of genes in a matter of minutes. We are moving at a breakneck pace. There are so many new developments that trials are competing for patients, ”he added.

“We have treatments that did not exist 5 years ago. We are not going to do the same in 5 or 10 years. It is an evolving field ”, underlined Dr Maurice.

“As we identify more mutations, we can develop treatments to target them,” said Dr Onugha. “We have significantly improved the way we treat lung cancer patients. The future treatment shows great promise and will have a huge impact on the survival of many lung cancer patients. “

Heredity can play a role in the development of lung cancer. However, most cases of lung cancer are not linked to inherited genetic mutations. Lung cancer tumors are usually associated with acquired genetic mutations.

After a diagnosis of lung cancer, doctors will examine the tumor for mutations that cause the cancer to grow. Biomarkers have paved the way for personalized treatment of lung cancer, and this area of ​​research is advancing rapidly.

Smoking remains the main risk factor for developing lung cancer.