According to the Centers for Disease Control and Prevention (CDC), roughly 10 to 20 percent of all lung cancer diagnoses in the United States happen in people with little to no history of smoking.

While there are multiple causes of lung cancer in nonsmokers, secondhand smoke and radon account for over 25 percent of these cases.

Almost all cases of lung cancer in nonsmokers are non-small cell lung cancer, which has a 5-year survival rate of over 60 percent if the cancer hasn’t spread to other tissues.

In this article, we will discuss what you need to know about lung cancer in nonsmokers, including symptoms, diagnosis, treatment, and more.

Many early symptoms of lung cancer are nonspecific, with no significant difference in lung cancer symptoms between smokers and nonsmokers. These early symptoms may include:

  • persistent cough
  • coughing up phlegm or blood
  • shortness of breath
  • wheezing or whistling breath
  • hoarse cough or voice
  • chest or back pain

When lung cancer has progressed, you may notice more severe symptoms, such as:

  • weakness or fatigue
  • loss of appetite
  • unexplained weight loss
  • chronic cough
  • breathing difficulties

When lung cancer has spread beyond your lungs, you may also notice other symptoms, depending on where the lung cancer has spread.

A 2020 research review showed that lung cancer in nonsmokers, or people who have smoked less than 100 cigarettes in their lifetime, can be caused by a variety of factors.

Increased age

Although it has been suggested that lung cancer in nonsmokers affects people who are younger, there has been no research to support this suggestion.

Instead, a 2017 study suggested that lung cancer in nonsmokers is more likely to be diagnosed in those who are older. This may be due to the increased length of environmental exposures over time.

Family history

Research shows that there’s an increased risk of lung cancer in nonsmokers who have a close family member with a lung cancer diagnosis.

In one 2010 study, almost 450 cases of lung cancer in nonsmokers were analyzed. Researchers found that having a first-degree family member who received a lung cancer diagnosis before 50 years old increased lung cancer risk.

In addition, lung cancer risk in nonsmokers is found to be higher if someone has a genetic mutation in the epidermal growth factor receptor (EGFR) gene.

According to the Lung Cancer Foundation of America, EGFR gene mutations can cause abnormal cell growth in your lungs, leading to the development of non-small cell lung cancer.

Environmental exposures

While there are many environmental exposures that can increase the risk of lung cancer, the most harmful exposures include:

  • secondhand smoke
  • asbestos
  • radon
  • chromium
  • arsenic

According to the CDC, of the 20,000 to 40,000 cases of lung cancer diagnosed in nonsmokers each year, secondhand smoke and radon account for more than 10,000 cases.

A 2014 research review showed a linear relationship between asbestos exposure and lung cancer, with increased exposure leading to increased risk.

Certain activities that expose your lungs to harmful fumes can also increase the risk of lung cancer, even in nonsmokers.

Chronic exposure to frying food, burning wood, or burning animal feces for fuel can greatly increase the risk of lung cancer.

Other illnesses

Other inflammatory lung conditions, such as pulmonary fibrosis, may increase the risk of lung cancer in nonsmokers.

Researchers have also suggested an increased risk of lung cancer due to certain viruses, including Epstein-Barr virus (EBV), human papillomavirus (HPV), and both hepatitis B and C.

However, more research is needed on these viruses and their association with lung cancer risk.

There are two types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

NSCLC is the most common type of lung cancer, accounting for roughly 80 to 85 percent of all lung cancer cases, according to the American Cancer Society (ACS). The most common types of NSCLC are:

  • adenocarcinoma
  • squamous cell carcinoma
  • large cell carcinoma

NSCLC, particularly adenocarcinoma, is the most common type of lung cancer diagnosed in nonsmokers.

SCLC is the less common type of lung cancer, accounting for only 10 to 15 percent of lung cancer diagnoses.

SCLC is more aggressive than NSCLC, but it tends to respond well to traditional cancer treatments. SCLC is very rarely diagnosed in people who have never smoked.

If you are concerned that you are experiencing symptoms of lung cancer, schedule an appointment with your doctor right away. Your doctor will determine if lung cancer might be the underlying cause by:

  • performing a physical exam
  • reviewing your medical history
  • ordering diagnostic testing

Imaging tests

Imaging tests allow your doctor to take images of the inside of your lungs, or other areas of your body, to determine if lung cancer is present. These tests may include:

Physical procedures

Physical procedures allow your doctor to take physical samples from the inside of your lungs to determine if cancer cells are present. These procedures may include:

All the testing included above can be used to determine many situations, including:

  • if you have lung cancer
  • what type of lung cancer you have
  • how far the lung cancer has spread

NSCLC can be treated with a combination of different therapies and approaches depending on the extent and nature of the cancer, as well as the person’s overall health. These treatment options may include:

  • Surgery. Surgery can be used to remove sections of your lung that may be affected by cancer. Surgery may involve a small or large portion of your lung and, in some cases, may even extend to other tissues where cancer has spread.
  • Chemotherapy. Chemotherapy is a type of cancer treatment that uses medications, administered orally or intravenously, to kill cancer cells. Chemotherapy can be used before or after surgery or combined with other types of treatments.
  • Radiation therapy. Radiation therapy is a noninvasive cancer treatment that uses high energy radiation to kill cancer cells. Radiation is often used in conjunction with other treatment options, such as chemotherapy. Radiation therapy is also used in cases where a person is not healthy enough to undergo surgery.
  • Targeted therapy. If you have developed lung cancer because of a genetic mutation, targeted drug therapy may be used as the first line of treatment. ALK inhibitors, EGFR inhibitors, and other targeted drugs can be used depending on what type of genetic mutation you have.

You will work with your doctor and team of specialists to determine the best course of treatment for your condition.

In recent years, treatment options for NSCLC have continued to improve the survival rates for people diagnosed with this type of cancer. According to the ACS, the 5-year relative survival rates for NSCLC are:

  • 63 percent for localized NSCLC
  • 35 percent for regional NSCLC
  • 7 percent for distant NSCLC

Although relative survival rates are helpful, they are not indicative of everyone’s condition.

Survival rates for an individual with cancer are affected by a variety of factors, including:

  • the type of cancer
  • time of diagnosis
  • overall health status

If you have recently received a diagnosis of lung cancer, you may be feeling anxious about what the future will bring for yourself and your loved ones.

Both psychotherapy and cancer support groups can be helpful in offering the following during this difficult time:

  • support
  • resources
  • hope

Many lung cancer symptoms are nonspecific, meaning that they can be due to a variety of conditions, not just lung cancer. For example, a persistent cough can be caused by:

  • allergies
  • an underlying virus
  • another related condition

However, if you have been experiencing symptoms that do not resolve with other treatments, reach out to your doctor for further testing.

While cigarette smoking is still the number one cause of lung cancer, nonsmokers include up to 20 percent of all lung cancer diagnoses each year.

NSCLC is the most common type of lung cancer in nonsmokers and smokers alike, with SCLC rarely being diagnosed in nonsmokers.

Know that treatment options for NSCLC have improved over the years and continue to increase both survival rates and quality of life in those who have been diagnosed.