When you hear about someone having lung cancer, you likely wonder – if not ask aloud – whether the person smoked. For a majority of lung cancer patients, smoking played a role in the development of their disease.
Yet a growing number of lung cancer patients – for reasons yet to be determined – are learning not all lung cancer is caused by inhaling nicotine and other chemicals found in tobacco.
Incidence of Lung Cancer in Nonsmokers
Research [1] cited by the National Institutes of Health indicates that between 10 and 15 percent of lung cancers develop in people who have never smoked. Additionally, the incidence of lung cancer among women who have never smoked is slightly higher than in men who have never smoked, according to published studies. Researchers warn, however, against concluding that non-smoking or never-smoking women are at a higher risk for lung cancer than their male counterparts.
Risk Factors
“We are seeing an increasing number of women, ages 50-70, who have never smoked being diagnosed with adenocarcinoma [2],” said Mark Dylewski, M.D. [3], a Baptist Health Medical Group [4]thoracic surgical oncologist with Miami Cancer Institute [5] and chief of general thoracic robotic surgery for Baptist Health’s Center for Robotic Surgery [6]. “But we don’t have a clear picture of why that’s the case. No research, so far, has shown any one factor these patients share.”
Dr. Dylewski says that some expected culprits include exposure to secondhand smoke or other toxins, genetic abnormalities, viruses, a family history of lung cancer and radiation from breast cancer treatment, which can show up 20 to 30 years later.
While no one wants to face a lung cancer diagnosis, the adenocarcinomas found in nonsmokers are generally slower-growing, and if caught early and treated, patients have a better prognosis. Conversely, small cell and squamous cell carcinomas, more often linked to smoking, tend to be more aggressive and difficult to treat.
Detecting Lung Cancer
With any type of cancer, early detection is key to survival. All too often, though, lung cancer remains symptomless until its advanced stages.
In 2013, the U.S. Preventive Services Task Force (USPSTF) began recommending yearly lung cancer screenings [7] for people, ages 55-80, who currently smoke or who have smoked the equivalent of one pack of cigarettes a day for at least 30 years and have quit within the past 15 years. During the screening, patients undergo a low-dose CT scan [8] of their chests.
For nonsmokers, however, there’s no recommendation for lung-cancer screenings, because no primary cause for these individuals has been identified. “We simply can’t screen every person without known risk factors,” Dr. Dylewski said.
That’s often why lung cancer in people who have never smoked shows up first on a chest X-ray, often ordered by a primary care physician for unrelated reasons. They’re not expecting to find lung cancer since they’ve never smoked.
Treating Lung Cancer Early
“These are the lucky ones,” Dr. Dylewski said. “When discovered on a chest X-ray before symptoms begin, lung cancer is often treatable.” He adds that lung cancer in nonsmokers responds well to new genetically-modulated chemotherapy in pill form. Surgical removal of the tumor is often easier in its early stages, too, and can be accomplished using robotic surgery.
“More studies are needed to determine why lung cancer is affecting people who have never smoked,” Dr. Dylewski said. “In the meantime, we need to be more aware and not discount lung cancer in this population.”