Lung cancer is the second most common cancer and the leading cause of cancer deaths in the United States. Most lung cancers are associated with lifestyle and environmental factors, such as smoking, air pollution, radiation exposure, and coal burning. But research has found that family history is also associated with lung cancer risk.

Studies on families with a history of lung cancer are looking at the combined involvement of genetics, shared lifestyles, and shared environment.

Lifestyle and environment

Lifestyle and environmental factors aren’t hereditary. However, they can be shared among family members. For example, if your parents were or are smokers, it may be more likely that you picked up the habit as well.

Cigarette smoking is the cause of most lung cancers. A 2017 research review states that 85 percent of lung cancer cases are thought to be caused by smoking. Tobacco smoke contains cancer-causing substances that damage your DNA and lead to lung cancer.

According to the Centers for Disease Control and Prevention (CDC), if you’re a long-time smoker, your risk of developing lung cancer is 15 to 30 times higher than it is for nonsmokers. However, 10 to 20 percent of people diagnosed with lung cancer are nonsmokers.

Other risk factors for lung cancer are air pollution and exposure to:

Alcohol consumption contributes to the risk of lung cancer. It’s thought that alcohol may increase the effects of the cancer-causing substances in tobacco smoke.

If you have HIV or lung diseases such as tuberculosis, emphysema, chronic bronchitis, you are also at a higher risk of lung cancer.

Genetics

Genetics do play a role in lung cancer. You may inherit an abnormal gene that could lead to lung cancer. Or you may inherit a gene that makes it harder for your body to get rid of the toxins in tobacco smoke. It’s important to know that in both cases, not smoking lowers your risk of developing lung cancer.

Most people who inherit the abnormal genes won’t develop lung cancer. If you have a genetic predisposition for lung cancer, quitting smoking will cut your risk in half, according to a 2016 international study.

The genetics of lung cancer is the subject of much ongoing research. A 2017 meta-analysis of lung cancer studies found that there were 22 genetic variants in 21 genes that showed strong evidence of contributing to lung cancer risk.

The question of genetic involvement is important in terms of developing targeted individualized therapies for lung cancer.

There are still uncertainties about the relative importance of genetic factors and smoking or secondhand smoke in terms of lung cancer risk.

Other risk factors

Other risk factors for lung cancer include your sex, race, and close family members with other cancers.

  • People with a family history of exposure to tobacco smoke are more likely to develop lung cancer if they’re female.
  • Black men are more likely to get lung cancer than white men.

Genetic testing and genetic mutations

Genetic testing is available to look for lung cancer risk. Ask your doctor or healthcare provider. You may want to check with your insurance company to see if genetic testing is covered.

The National Cancer Institute recommends genetic testing if:

  • you have a family history indicating cancer risk
  • the results will show whether a genetic change is present
  • the results will help guide your future medical care

A genetic test takes a small sample of your tissue or a bodily fluid and sends it to a specialized laboratory for analysis.

There’s debate in the medical community about whether genetic testing results for lung cancer will change the behavior of smokers if they find out that they’re at risk. The argument is that you probably shouldn’t get tested if you’re not going to do anything to decrease your risk.

If you’re already diagnosed with lung cancer, genetic testing is still advised, as it can pinpoint particular genetic mutations. Many targeted treatments are now available or being researched for specific mutations.

Screening and diagnostic tests for lung cancer

For people at high risk of lung cancer, screening using a low-dose CT scan is recommended. A large-scale national study, the National Lung Screening Research Trial, concluded in 2010 that CT screening significantly reduced the rates of “both death from lung cancer and death from any cause.”

The study found that CT scan screening lowered deaths from lung cancer by 20 percent compared with chest X-ray screening.

Diagnostic tests when cancer is suspected include:

  • biopsy with a needle
  • examination of mucus (sputum) coughed up from your lungs to detect cancer cells
  • bronchoscopy, which involves inserting a tube through your mouth or nose down to your lungs
  • CT scan, X-ray, PET scan, MRI scan, or sonogram

The No. 1 way to reduce your risk of lung cancer, including heritable lung cancer, is to stop smoking and avoid secondhand smoke.

Other measures you can take are:

  • Limit your exposure to radon, a naturally occurring gas in the earth and rocks. Check the level of radon in your house and take steps to lower it if it’s high.
  • Limit your exposure to cancer-causing materials at work, such as asbestos, diesel fuel, and heavy metals.
  • Get a CT scan, which can catch tumors early

There’s no clear evidence that taking things such as beta carotene supplements or vitamin E will reduce your lung cancer risk.

It’s also not clear if diet has an effect on risk, but a healthy diet is beneficial in general.

There is some evidence that exercise reduces the risk of lung cancer in smokers and former smokers. The National Institutes of Health reported on a 2006 study that found women who had a high physical activity level were 23 percent less likely to develop lung cancer than women who had low physical activity.

Lung cancers most often don’t cause any symptoms until they’ve spread. But the earlier the lung cancer is found, the better your outcome. It’s important to see your doctor if you have any symptoms.

Here are the most common lung cancer symptoms to look for:

If lung cancer has spread to other organs or tissues, it may cause:

  • bone pain
  • changes in your nervous system from cancer spread to the brain or spine
  • yellowing of your skin or eyes from cancer spread to the liver
  • lumps on your body from cancer spread to your skin or lymph nodes

It's likely that these symptoms have other causes. But in any case, see your doctor for a diagnosis and treatment.

According to the American Cancer Society, sometimes the first symptoms of lung cancer are caused by hormone-type substances that the cancer produces that affect other tissues and organs. These symptoms are collectively called paraneoplastic syndromes.

Some kinds of lung cancer cause other specific syndromes of symptoms:

All of these symptoms are likely to have other potentially serious causes, so see your doctor for diagnosis and treatment.

Lung cancer is responsible for 27 percent of all cancer deaths. In 2011, there were an estimated 221,130 new cases and 156,940 deaths from lung cancer. The overall lung cancer five-year survival rate is 17.7 percent. However, survival rates vary depending on the type of lung cancer and the stage at diagnosis.

New targeted treatments are being developed that show promise for lung cancer. For those with lung cancer that’s diagnosed in an early stage and treated with surgery, the survival rate is better. According to the American Lung Association, the five-year survival rate is 55 percent for people whose lung cancer hasn’t spread beyond the lungs. The organization also reports that about 16 percent of lung cancers are diagnosed at an early stage.