Lung cancer: It’s not just about smoking

Estimated reading time: 5 minutes

By Nicole Brudos Ferrara

In the U.S. alone, the National Cancer Institute estimates that lung cancer accounts for 12% of new cancer cases annually. And more than 21% of all cancer deaths in the U.S. in 2021 were likely caused by lung cancer. To quote the Centers for Disease Control and Prevention (CDC), lung cancer is the biggest cancer killer in both men and women.

Who is at risk?

People who smoke have the greatest risk of developing lung cancer, but it can occur in people who don't smoke, as well.

"That's one of the misconceptions," says Aaron Mansfield, M.D., a medical oncologist at Mayo Clinic who specializes in lung cancer. "Although tobacco use is clearly the largest risk factor to develop lung cancer, there are many other risk factors, and risk factors we don't know. All you need to be at risk of developing lung cancer is a lung."

Exposure to secondhand smoke also can increase the risk of lung cancer. "We know that exposure to tobacco smoke will increase your risk," says Dr. Mansfield. "But it's lower for those who don't smoke than for those who actually did the smoking. And the risk goes down with time from the end of your last exposure."

Other risk factors for lung cancer include exposure to radon gas, asbestos and other carcinogens. "One of the other risk factors is radon, and that was proven by looking at miners who had mined uranium," says Dr. Mansfield. "Also, when patients have a history of tobacco use and asbestos exposure, there's a synergistic increase in the risk to develop lung cancer."

Some people diagnosed with lung cancer don't have any obvious risk factors. "For some patients, especially the younger, healthier ones who don't have tobacco exposure, we have difficulties identifying what that actual risk factor is," says Dr. Mansfield.

What are the symptoms, and how is it diagnosed?

Symptoms of lung cancer, such as shortness of breath and chest pain, can be mistaken for pneumonia.

"Many of my patients have been diagnosed as having pneumonia," says Dr. Mansfield. "They've received many rounds of antibiotics that were not beneficial. They make their way to us when a mass that was thought to be pneumonia on a chest X-ray never improved."

A persistent cough, coughing up blood, weight loss, bone pain and headache also can be symptoms of lung cancer.

Getting an accurate diagnosis typically involves a biopsy. "We like tissue to make a solid diagnosis," says Dr. Mansfield. "We use ultrasound or CT to guide where to place the needle to get the most accurate tissue sample."

Screening saves lives

Detecting lung cancer early is key to a successful outcome. "The holy grail, so to speak, is to find it at the earliest stage possible, where it can be surgically removed or treated with radiation and ablation for a cure," says Karen Swanson, D.O., a pulmonologist and critical care specialist at Mayo Clinic.

But that's often not the case because symptoms of lung cancer rarely appear until the cancer has advanced into other areas of the body. "One of the problems with lung cancer is that by the time a patient is diagnosed with lung cancer ― 80% of the time ― the lung cancer has spread, meaning it's not localized disease," says Dr. Swanson.

"Unfortunately, when tumors grow within our lungs, it's not something our bodies can sense or feel," says Dr. Mansfield. "So, we miss it at its earliest stages, unless we screen."

Screening for lung cancer with an annual low-dose CT scan saves lives and is recommended for those at high risk. "Patients should talk to their primary care provider about lung cancer screening, especially if they have any history of smoking," says Dr. Swanson.

The U.S. Preventive Services Task Force recently lowered the lung cancer screening guidelines from age 55 and a 30-pack year history to age 50 and a 20-pack year history to catch more lung cancers sooner. A pack year measures how many cigarettes a person has smoked over a period of time, calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked.

Get help to stop smoking

If you smoke cigarettes, you can reduce your lung cancer risk by quitting. "Thirty percent of all cancer-related mortality is caused by smoking. Even if you're in your 60s, or 70s, we know that by quitting smoking you add years of life and reduce the chronic health impacts and symptoms that occur from smoking," says J. Taylor Hays, M.D., an internist at Mayo Clinic and associate director of the Mayo Clinic Nicotine Dependence Center.

"Even people who've had chronic bronchitis and other things, they see within months to years significant reduction in symptoms, significant improvement in shortness of breath, and the ability to function without symptoms," says Dr. Hays.

Quitting cigarettes isn't easy, so it's best to do it with help. "Nicotine is very addictive," says Dr. Mansfield. "We have resources to help with that."

If you smoke, talk to your primary care provider about screening for lung cancer and resources to help you quit smoking.

Fortunately, advancements in medical science are improving outcomes for people diagnosed with lung cancer. "The improvements in lung cancer screening, targeted therapies, and immunotherapies have all improved lung cancer mortality overall," says Dr. Mansfield.

Watch Dr. Mansfield discuss screening, diagnosis and treatment for lung cancer on this "Mayo Clinic Q&A" podcast:

Learn more about lung cancer, and learn more about how to quit smoking.

Find a lung cancer clinical trial.

Join the Lung Cancer Group on Mayo Clinic Connect.