Lung cancer is by far one of the leading causes of death in men and women. “If you add up all the deaths from the next several most common causes of cancer deaths, it does not equal lung cancer,” says Dr. David Carbone, director of the Thoracic Oncology Center at The Ohio State University Comprehensive Cancer Center.
There were nearly a quarter million new cases of lung cancer in the U.S. in 2016, according to the National Cancer Institute. This accounted for about 13 percent of all new cancer cases. The NCI estimates about 6.5 percent of men and women will develop lung or bronchus cancer (a rare type of lung cancer) at some point in their lives.
[See: 7 Innovations in Cancer Therapy.]
Smoking Causes Most Lung Cancers
Although lung cancer was actually quite rare a century ago, it’s now a major cause of death and has surpassed heart disease as a leading cause of smoking-related mortality. “About 85 percent of people who get lung cancer had some smoking experience, and more than half — maybe even two-thirds — of new lung cancer diagnoses today [are in people who] have quit smoking,” Carbone says. Some of these former smokers quit within the past few years; others quit 30 or more years ago.
The NCI estimates that current smokers have, on average, a 20 times greater risk for lung cancer than nonsmokers. In fact, smoking is a significant risk factor for many other types of cancer as well. The younger you are when you start smoking, the greater your risk. Exposure to secondhand smoke is also a risk factor for lung cancer.
There are many carcinogens, or cancer-causing agents, in cigarette smoke, explains Dr. Leena Gandhi, director of thoracic medical oncology at NYU Langone Medical Center. These carcinogens damage your DNA and can lead to cancer. “This link [between smoking and cancer] has been demonstrated over and over. Cancer is more common in areas [of the body] that accumulate or experience smoke, so smoking-related cancers are also seen in the head and neck and the bladder, as the carcinogens are excreted. Fortunately, because the smoking incidence is changing, especially in North America, we’re seeing the overall rates of lung cancer stabilizing and leveling off.”
Despite an overall decreasing trend in lung cancer, there’s been a recent uptick, and electronic cigarettes may be to blame. Gandhi says it’s too early to say what effect e-cigarettes will have on lung cancer, but she worries that they may be a gateway to actually smoking.
[See: 7 Things You Didn’t Know About Lung Cancer.]
Genetics and Environmental Toxins
Exposure to other environmental toxins and carcinogens likely explains why 10 to 15 percent of lung cancers occur in people who have never smoked. These substances may cause genetic changes that affect how cells function, which can lead to uncontrolled cell growth.
Radon, a colorless, odorless gas produced from the breakdown of naturally occurring uranium in the soil, might be associated with an increased risk in lung cancer. Unfortunately, studies linking radon and lung are not conclusive, so it’s hard to establish a causal link between the two, Gandhi says.
Ionizing radiation (for example, from X-rays and gamma rays), asbestos and air pollution may also increase your risk of lung cancer. The more you’re exposed, the greater your risk. This is especially true if you also smoke. According to the NCI, cigarette smoking amplifies the carcinogenic effects of radiation.
Genetics also play a role. Gandhi says researchers are beginning to identify specific genetic mutations linked to lung cancer. For example, about 10 percent of patients with Non-Small Cell Lung Cancer (which accounts for 85 percent of lung cancers) have tumors associated with a mutation called EGFR. Most of these tumors occur in people who never smoked. This genetic mutation does not seem to overlap with other genetic mutations, making it a good target for lung cancer therapies in this subset of patients.
[See: What Not to Say to Someone With Lung Cancer.]
Just Don’t Do It
You can significantly lower your risk of developing lung cancer by not smoking, or by quitting if you already smoke. The American Institute for Cancer Research estimates we could prevent about 200,000 cases of lung cancer each year if it weren’t for tobacco use. “Even if you quit at the time of your diagnosis of lung cancer, you can have longer survival and better prognosis,” Gandhi says.
Of course, not everyone who smokes, or who inhales secondhand smoke, will develop lung cancer, and not everyone who develops lung cancer was a smoker. And simply being exposed to cancer-causing agents doesn’t necessarily mean you will develop cancer. Cancer is a complex disease.
“The stigma that lung cancer only affects smokers is unfair,” Carbone says. Approximately 20,000 never smokers in the U.S. develop lung cancer each year. “If you have lungs, you can get lung cancer.”
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