You probably feel that you’re not at risk for lung cancer because you’ve never smoked. Even though not smoking is a very smart path to take for your overall heath, there is no guarantee for so-called “never-smokers.” In fact, lung cancer worldwide in people who have never smoked comprises an estimated 15 to 20 percent of cases in men and over 50 percent in women.
“It’s important to understand that never-smokers represent an increasingly high proportion of lung cancer cases,” says Juan Carlos Batlle, M.D.,  chief of thoracic imaging at Baptist Health South Florida. “Because lung cancer is the leading cause of cancer deaths, never-smokers with lung cancer outnumber other people with certain common cancers, such as certain leukemias or lymphomas, and ovarian cancers and cervical cancers. Never smokers with lung cancer as a number is higher than many of these other groups. So we can’t dismiss this.”
While it’s important for never-smokers to realize their risk for lung cancer (see non-smoking risk factors below), it’s smokers and former smokers who have the most to fear. Tobacco represents a toxic mix of more than 7,000 chemicals, according to the U.S. Centers for Disease Control and Prevention (CDC). “Many are poisons. At least 70 of the chemicals are known to cause cancer in people or animals, says the CDC.
Smoking represents, by far, the largest risk factor for lung cancer, and smoking is responsible for more than 80 percent of diagnosed cases. Most significantly, lung cancer is the No. 1 killer among all cancers. That high volume of deaths associated with lung cancer is most troubling, especially since the overall smoking rate in the United States has fallen to about 15 percent, down from nearly 50 percent in the 1960s.
Over the past few years, “vaping,” or smoking e-cigarettes, has increased in popularity, especially among teenagers. And that’s a disturbing trend, since traditional tobacco use tends to also start at a very young age.
“Many people start smoking in their teens when they’re young and impressionable,” says Dr. Batlle. “Unfortunately, cigarettes are addicting and people end up with this life-long problem.”
But there is a misconception among smokers and ex-smokers, says Dr. Battle. “There are certain people who think that they are too far gone. They think: ‘I’ve smoked for 40 years and there’s nothing that can be done.’ But not smoking can decrease your risk of dying from cancer, regardless of when you quit. You’re still at lower risk than someone who continues to smoke.” In fact, ex-smokers who have gone 15 years without lighting up share nearly the same risk of developing lung cancer as non-smokers, he said.
Low-Dose CT Lung Screenings
A procedure recently made more widely available — the low-dose CT lung cancer screening  — is helping save the lives of recent ex-smokers. Three years ago, the U.S. Preventive Services Task Force (USPSTF) approved annual low-dose CT lung cancer screenings for adults ages 55 through 80 who have a “30 pack-year” history of smoking (described as a pack a day for 30 years; two packs a day for 15 years, and so on), or who have quit smoking in the past 15 years. That means that most health insurers are covering these screenings at little to no cost for ex-smokers who qualify.
Dr. Batlle says that society has created a “stigma” that is preventing some ex-smokers to take the necessary action, such as seeking out this screenings, which are quick, safe, non-invasive and affordable.
“Ex-smokers have been unfairly stigmatized for their behavior,” says Dr. Batlle. “They feel that since they smoked, nobody cares about them. But we need to remove that stigma. And make it easier for them to make the choice to get screened.”
Non-Smoking Risk Factors for Lung Cancer
While staying away from tobacco products is the top way of avoid a higher risk of lung cancer. There are other risk factors that have been discovered over the years tied to lung cancer diagnoses. Here are the top non-smoking risk factors for lung cancer, according to the American Cancer Society:
Radon gas. A colorless, odorless and radioactive gas that is produced from a natural breakdown of uranium in soil, rock and water, radon occurs naturally outdoors in harmless amounts and sometimes becomes concentrated in homes built on soil with natural uranium deposits. Studies have found that the risk of lung cancer is higher in those who have lived for many years in a radon-contaminated house.
Secondhand smoke. Each year, nearly 8,000 adults die of lung cancer as a result of breathing secondhand smoke. Laws that ban smoking in public places have helped to reduce this danger.
Cancer-causing agents at work. For some, the workplace is a source of exposure to carcinogens such as asbestos and diesel exhaust. Work-related exposure to such cancer-causing materials has waned in recent years, as the government and industries have taken more steps to protect workers.
Air pollution. Both indoor and outdoor air pollution can contribute to lung cancer. In 2013, the World Health Organization (WHO) classified outdoor air pollution as a cancer causing agent (carcinogen).
Gene mutations. New research is revealing more about what causes cells to become cancerous, and how lung cancer cells differ between non-smokers and smokers. One specific type of gene mutation is much more common in lung cancer in non-smokers than smokers. This mutation activates a gene that normally helps cells grow and divide.