Both environmental and genetic factors can contribute to lung cancer, which develops as a result of cells in the lungs multiplying uncontrollably.
Lung cancer is the
In recent years, testing cancerous lung tumors for genetic mutations has become a crucial step in diagnosing and treating lung cancer.
Experts who study the genetic mutations involved in lung cancer note that environmental and hereditary risk factors play a role.
According to the
In the United States, only
The Environmental Protection Agency (EPA) estimates that radon, the second most common cause of lung cancer, is responsible for the death of about 21,000 people every year, about 2,900 of whom have never smoked.
Other environmental factors associated with lung cancer include exposure to:
- outdoor and indoor air pollution
- asbestos
- heavy metals
- industrial emissions
- pesticides
- radiation therapy to the chest
Inherited DNA mutations increase the risk of some types of cancer and may play a role in lung cancer.
The most common form of lung cancer that occurs in nonsmokers is adenocarcinoma, which researchers have linked to ALK and EGFR mutations. For instance, in a 2017 study, rates of ALK and EGFR mutations were higher among the participants who had never smoked than among current smokers.
The
The ACS explains that experts do not believe that inherited genetic mutations alone cause many lung cancers. The 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 Saint John’s Cancer Institute at Providence Saint John’s Health Center in Santa Monica, CA.
“Genetics play a role, but we’re not sure exactly what kind of role at this point,” Dr. Onugha told Medical News Today.
“We don’t have genetic screening [of healthy individuals] as there is, for example, with breast cancer. For a patient with BRCA mutations, we know there’s an increased risk of breast cancer and other cancers. We don’t have that same corollary with lung cancer and inherited gene mutations,” he continued.
“That’s what we know right now. Ten years from now, we may say that a certain mutation does mean you have a particular risk of lung cancer,” said Dr. Onugha.
“There is some combination of environmental and occupational exposure and genetics. That’s why some heavy smokers don’t get lung cancer, and some who smoke a little do,” he concluded.
Dr. John Maurice is a thoracic surgeon and lung cancer specialist at the Center for Cancer Prevention and Treatment at Providence St. Joseph Hospital in California.
“There’s definitely a familial lung cancer trait we haven’t yet sifted through enough to understand those genes,” Dr. Maurice told MNT.
“Someone with lung cancer having a relative with lung cancer is pretty common. Sometimes, we can identify something there. There’s a weakness in the gene repair mechanism, or the gene has a characteristic that gets mutations easier compared to others with a more robust repair mechanism,” he said.
“We don’t really understand how all factors combine to produce a cancer,” added Dr. Maurice.
Secondhand 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 lung cancer risk in children, as a review article in Translational Lung Cancer Research discusses. However, the exact roles of various genetic, environmental, and occupational exposures in an individual are difficult to determine.
According to the
- 20–25% of non-small lung cancers (NSCLCs) involve changes in the KRAS gene
- 10–20% involve the EGFR gene
- 5% involve the ALK gene
Other biomarkers associated with lung cancer include:
- ROS1
- RET
- BRAF
- MET
Research from 2020 found that EGFR mutations are more common among nonsmokers with lung cancer than among smokers with the disease. Other common genetic mutations in nonsmokers with NSCLC are ALK and KRAS.
The authors of a 2017 retrospective study concluded that lung cancer in never-smokers is understudied. They also noted that the prevalence of lung cancer in never-smokers has been increasing.
“We started detecting the first genetic anomalies associated with lung cancer about 15 years ago with EGFR mutations,” said Dr. Maurice. “Every single person and every single tumor has a different set of mutations, and they sometimes change over time.”
Dr. Onugha explained that experts’ discussion of cancer and genetics typically refers to factors that cause some familial pattern.
“In lung cancer, generally, we’re talking about tumor biology. We refer to these tumor mutations as 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 nonsmokers can have different mutations. Treatment now is personalized according to your tumor biology,” noted Dr. Onugha.
“We’re talking about a field that has gone wild with developments,” said Dr. Maurice.
“Gene sequencing used to take a long time. Now you can check thousands of genes in minutes. We’re moving forward at breakneck pace. There are so many new developments that trials are competing for patients,” he added.
“We have treatments that didn’t exist 5 years ago. We’re not going to be doing the same thing 5 or 10 years from now. It’s an evolving field,” Dr. Maurice pointed out.
“As we identify more mutations, we can develop treatments to target them,” said Dr. Onugha. “We have improved in a significant way how we treat patients with lung cancer. Future treatment is very bright and will make a huge impact in survival for many patients with lung cancer.”
Heredity may play a role in the development of lung cancer. However, most cases of lung cancer are not linked to inherited gene mutations. Lung cancer tumors are usually associated with acquired gene mutations.
After a diagnosis of lung cancer, doctors will check the tumor for mutations that drive the cancer’s growth. Biomarkers have paved the way for personalized treatment for lung cancer, and this field of research is advancing rapidly.
Smoking remains the single biggest risk factor for developing lung cancer.
