Why Does Lung Cancer Occur in Non-Smokers?

Daniel Marcus';

By Daniel Marcus

Posted on March 28th, 2021 in News, Myths & Tips

By the end of the year, over 235,000 people in the United States will have received a diagnosis of lung cancer. Lung cancer is currently the leading cause of cancer death, accounting for approximately 25% of the total number of demises caused by malignant diseases.

Today, it is a known fact that tobacco smoking is responsible for up to 90% of lung cancer cases, as cigarette smoke contains 250 harmful chemicals, out of which 69 are carcinogens. However, there are people who have never smoked a cigarette in their lives, yet still come to struggle with lung cancer, which leads to the question: why does lung cancer occur in non-smokers?

According to the American Cancer Society, nearly 20% of people diagnosed with lung cancer throughout the country – or 30,000 individuals – are not smokers.

By definition, non-smokers are people who have never used tobacco products or who have smoked fewer than 100 cigarettes during their lifetime. It is worthy of note that non-smokers tend to develop a different type of lung cancer than smokers, which is usually the consequence of a genetic mutation or abnormality.

This is good news, as the treatment available for this type of lung cancer is significantly more effective than that used to keep lung cancer caused by smoking under control, and may even lead to a faster remission of the disease, eventually.

What Are the Causes of Lung Cancer in Non-Smokers?

In the majority of cases, when lung cancer develops in a non-smoker, there are multiple factors that lead to the occurrence of the disease. A common precursor is a genetic mutation that is also known as a “somatic” mutation, which significantly contributes to the development of lung cancer in non-smokers.

It is noteworthy that this is different than a “germline” mutation, which is present in all of the normal DNA. There are numerous reputable medical studies that found that somatic mutations or abnormalities may play a crucial role in the growth of lung cancer in non-smokers.

In addition to genetic factors, there are also several environmental factors whose presence may contribute to the development of lung cancer in non-smokers, such as exposure to:

  • radon gas: as one of the leading causes of lung cancer in non-smokers, radon gas is the culprit behind approximately 21,000 deaths caused by lung cancer annually, and it is a gas that has no smell and that occurs naturally outdoors, but can easily accumulate in buildings located on uranium deposits
  • secondhand tobacco smoke: if you live under the same roof as smokers, you are inevitably exposed to secondhand tobacco smoke, which increases your risk of developing lung cancer significantly, as secondhand tobacco smoke is responsible for the deaths of 7,000 people every year
  • workplace carcinogens: industrial workers are often exposed to occupational carcinogens such as asbestos, diesel exhaust, or heavy metals, whose presence in the body may result in the occurrence of lung cancer over the years
  • air pollution: while air pollution is not a major cause for concern in the United States, people who live in countries where there is heavy air pollution are more susceptible to coming to struggle with lung cancer

The presence of human papillomavirus (HPV), which currently occurs in 79 million people in the country, is another risk factor for lung cancer, particularly among non-smoker women. Since the 1980s, there have been a series of medical studies examining the connection between HPV and lung cancer in non-smokers, but no definitive causal relation has been found yet.

Nevertheless, if you are infected with HPV, you may want to keep a close eye on your health and, in the regrettable event that you experience symptoms that may indicate lung cancer, you should immediately seek medical attention.

The Differences Between Lung Cancer in Smokers and Lung Cancer in Non-Smokers

Often starting in the outer layers of the lungs, adenocarcinoma is the most common type of lung cancer non-smokers develop. It usually occurs in the bronchioles, the cells that line the small airways and produce mucus. On the other hand, smokers usually develop squamous cell carcinoma. One of the major differences between adenocarcinoma and the types of lung cancer smokers come to struggle with concerns the shape of the damaged lungs.

Another essential difference between smokers’ lung cancer and non-smokers’ lung cancer is that the latter tends to grow more slowly and is less likely to spread to adjacent parts of the body. However, it can still recur after the patient had the affected parts of the lungs removed surgically. It is important to know that women who have never smoked are more likely than non-smoker men to develop lung cancer. Furthermore, lung cancer in non-smokers is often diagnosed at a younger age compared to smokers. Lastly, a sliver of hope is that non-smokers with lung cancer typically live 56% longer than smokers with this malignant disease.

How to Avoid Developing Lung Cancer as a Non-Smoker

Two essential things you can do to drastically reduce your lung cancer risk as a non-smoker is to check your home for the presence of radon gas and to avoid exposure to secondhand tobacco smoke. Moreover, including certain foods in your diet, such as garlic, apples, broccoli, and green tea, may also lower your chances of being diagnosed with lung cancer.

Finally, if you work in one of the following occupations, you need to make sure that you are always wearing adequate protective equipment, as these jobs imply exposure to toxic agents that may cause lung cancer:

  • truck driving
  • sandblasting
  • metalworking
  • ceramic making
  • uranium mining
  • glass manufacturing

It is estimated that, in the United States, workplace toxic exposure is responsible for lung cancer in between 13% and 29% of non-smoker men and in 5% of non-smoker women. However, wearing protective equipment at all times will result in little to no toxic exposure if you have one of the above occupations.