Lung cancer is the second most common cancer in the United States, outpaced only by breast cancer. In 2015, an estimated 221,000 people learned they have lung cancer, according to the American Cancer Society. That’s about one in 13 men and one in 16 women.

Lung cancer awareness continues to grow, thanks to a surge of scientific research and aggressive public awareness campaigns about the harms of cigarette smoking and the health benefits of quitting.

Understanding the causes of lung cancer, prevention strategies and recommendations for early detection are powerful steps in lowering your and your family’s risk of the disease.

What Causes Lung Cancer?

Cigarette smoking is the No. 1 risk factor for lung cancer, causing about 90 percent of lung cancer cases.

“Every time you inhale cigarette smoke, you breathe in chemicals that damage your lung tissue and can turn normal cells into cancer cells over time,”says Julie Brahmer, a board-certified medical oncologist and director of the Lung Cancer Program at the Johns Hopkins Kimmel Cancer Center.

Other causes of lung cancer, in addition to cigarette smoking, include:

• Smoking pipes and cigars

• Inhaling secondhand smoke

• Exposure to radon, a radioactive gas found in the ground that can seep into groundwater and homes

• Exposure to asbestos, a naturally occurring mineral found in some commercial building products

Preventing Lung Cancer

The best prevention for lung cancer is to stop smoking — or never start.

In fact, cigarette smoking is the leading cause of preventable diseases in the country, according to the Centers for Disease Control and Prevention. Quitting smoking has immediate health benefits that help minimize a person’s risk of developing lung cancer.

“From reduced blood pressure and heart attack risk to increased lung function and energy levels, your whole body starts to function better when you stop smoking,” says Brahmer.

Limiting exposure to radon is another prevention strategy. Surprisingly, exposure to radon is the second most common cause of lung cancer in the nation, after smoking. Radon comes from the ground and can seep into groundwater and into homes, through cracks in the foundation. Fortunately, radon test kits are readily available online and in some home improvements stores. If you find high levels of radon in your home, you can install a mitigation system that seals cracks and joints and purifies water for drinking, food preparation and bathing.

Exercising and eating a healthy, balanced diet also help reduce the risk of cancer. When you stay fit and active, it’s easier to maintain a healthy weight, which is important in preventing chronic disease, like cancer. As a general rule of thumb, people should aim to keep their body mass index (BMI) below 25. If you’re unsure of your BMI, visit our Health Library or call your doctor’s office to find out. Eating a well-balanced diet that meets all of your nutritional needs while limiting high-fat or processed foods also helps to lower your cancer risk.

While these preventive measures may lower your risk, there’s no definitive way to prevent lung cancer. Lung cancer screening for people at high risk of developing lung cancer offers hope for early detection, when surgery offers a possible cure.

How to Detect Lung Cancer Early

When lung cancer is caught early, it’s easier to successfully treat the disease using effective and appropriate treatment.

Aimed at improving early detection of lung cancer, a recent national lung screening trial looked at the benefits of using a low-dose CT scan, rather than a typical chest X-ray, to screen for lung cancer. Compared to a traditional CT scan, a low-dose scan produces five times less radiation. As it turns out, the study found that people who were screened with the low-dose CT scan had a greater chance of survival than those who got standard chest X-rays.

Soon after the results of this massive clinical trial were published, the U.S. Preventive Services Task Force put new guidelines in place, recommending yearly lung cancer screening using low-dose CT scans for people who are considered at high risk for developing lung cancer.

“Screening really is our best tool to find lung cancer before it advances into serious stages,” says Brahmer.

People considered at high risk for developing lung cancer:

• Have a history of heavy smoking (smoking at least one pack a day for 30 years).

• Are current smokers or former smokers who quit within the past 15 years.

• Are between the ages of 55 and 80.

If your doctor detects anything abnormal during a lung cancer screening, diagnostic tests, including other scans and biopsies (lung tissue samples), are the next step. Read more about prevention, diagnosis and treatment at Johns Hopkins.