Why do nonsmokers get lung cancer?


Research is trying to determine why nonsmokers can get lung cancer, too.

Smoking is a well-known risk factor for lung cancer, but at least 10 to 20 percent of lung cancer cases are found in nonsmokers. Rates among nonsmokers have been rising since 1990.

In addition to tobacco products, what causes lung cancer?

Research is ongoing in this area, and we hope to learn more. Currently, the other known causes of lung cancer include:

  • Secondhand smoke (or passive smoking)
  • Exposure to certain carcinogens, such as asbestos, radon, ionizing radiation, arsenic, chromium, nickel, polycyclic aromatic hydrocarbons, and indoor and outdoor pollutants, among others
  • Some pre-existing lung diseases such as chronic obstructive pulmonary disease, pulmonary fibrosis, and human immune deficiency virus (HIV)
  • Family or personal history of lung cancer
  • Personal history of other types of cancer and related treatments
  • Genetic predisposition

What do we know about lung cancer in nonsmokers?

There is a clear gender gap – the majority of lung cancers in lifelong nonsmokers affect females. Cancer research and clinical experience point toward different trends and behaviors among lifelong nonsmoker females with lung cancer.

Scientists believe these differences are most likely caused by differences in tumor biology. Lung cancer in nonsmokers is more common among young women of Asian/Pacific Island ethnicity; however, it can affect anyone.

How do I know if my symptoms are lung cancer?

Cancer is one of many types of lung disease. If you have excessive coughing, chest pain, shortness of breath, or wheezing, or if you are coughing up blood, these are signs that you should see a doctor and be evaluated.

Recurrent pneumonia with symptoms of infection such as fever, chills, and coughing excessive sputum is a warning sign as well.

Tests to diagnose lung cancer include:

  • Imaging tests – These can include a computed tomography (CT) scan, which can reveal small lesions on your lungs that X-rays might not detect; a PET scan, which can help differentiate between normal tissues and cancer; a bone scan; and magnetic resonance imaging (MRI) of different body organs.
  • Bronchoscopy – Clinicians use this outpatient procedure to look into the airways for abnormalities. Sometimes X-ray or ultrasound and CT are used during the procedure.
  • Biopsies – These are tissue samples from lung nodules, lung masses, lymph nodes within the chest, and other lesions within or outside the chest. A biopsy can be done under imaging guidance or during bronchoscopy.
  • Biomarkers – In this promising and rapidly growing new field, scientists are working on developing tests for saliva, mucus, and blood that can help detect lung cancer early. Screening these samples using biological markers (biomarkers) is currently being studied as a complement to imaging tests.

Is there a difference in lung cancer treatments for nonsmokers?

In general, people who have never smoked are more likely to have specific genetic mutations for which there are targeted treatments. Never-smokers are more likely to have EGFR and ALK mutations, which can be identified when a tumor is biopsied. Unfortunately, there are no genetic tests to identify those mutations prior to the appearance of the tumor. They are determined only after the tumor is identified.

For those who don’t have these mutations, the same standard of care that current smokers and former smokers receive is available. Traditional treatments for lung cancer can include medications, surgeries, and radiation treatments, or combinations of those.

Chemotherapy, which can be used before or after surgery, involves powerful medications that kill rapidly dividing cells such as cancer cells. Some medications target specific mutations in cancer cells that are not found in normal cells. There are also immunotherapy drugs that “boost” the immune system, enabling a patient’s own white blood cells to recognize and destroy cancer cells.

Surgical solutions can include:

  • Pneumonectomy, the surgical removal of the entire lung
  • Lobectomy, which removes an entire section or lobe of a lung
  • Segmentectomy or wedge resection, which removes part of a lobe

Radiation can be given as a primary treatment either before surgery to shrink a tumor and make it easier to remove or after surgery to further decrease the chance of cancer recurrence. Research here has shown that inoperable patients such as the frail and elderly have a very high (97 percent) chance of cure of their primary tumor with stereotactic radiation, a giant improvement over the 30 to 40 percent tumor control rate with conventional therapy. 

Other radiation therapy treatments include:

  • High-dose rate (HDR) brachytherapy for tumors growing inside the air space of the lung. Intensity-modulated radiation therapy (IMRT), which allows doctors to use multiple radiation beams of varying lengths and intensity.
  • Stereotactic ablative radiotherapy (SABR), which involves one or a few high-dose applications of radiation to a tumor instead of the many smaller doses given in standard radiation treatment.

Also worth consideration are clinical trials. Through clinical trials, patients can gain access to treatments not available elsewhere. We are part of the National Cancer Institute’s National Clinical Trials Network, which provides patients access to NCI-sponsored cancer research trials in which promising new drugs often are tested.

Other aspects to consider when evaluating your treatment options include having a dedicated patient coordinator who can help you navigate the process, as well as support teams that might include pain specialists, psychologists, social workers, dietitians, financial counselors, and specially trained nurses.

Fortunately, our arsenal of tools for diagnosing, staging, and treating lung cancer has developed significantly over the last few decades. Whether you are a current smoker, former smoker, or nonsmoker, it’s important to learn about your options.

Looking for more information? Our Lung Cancer Guide offers information about support programs, treatment options, and more.