Reasons of lung cancer behind smoking?


Lung cancer is a formidable health concern, with smoking often taking the blame as its leading cause. However, it’s crucial to recognize that not all cases of lung cancer are linked to tobacco use. In this article, we will explore the various possible causes of lung cancer beyond smoking, shedding light on other risk factors and environmental exposures that contribute to the development of this devastating disease.

1. Radon Gas Exposure

Radon is a colorless, odorless, and tasteless radioactive gas that naturally occurs in the Earth’s soil and rocks. According to the U.S. Environmental Protection Agency (EPA), radon-induced lung cancer is the second leading cause of the disease, after smoking. It is estimated to be responsible for about 21,000 lung cancer deaths in the United States each year.

2. Occupational Hazards

Certain professions and workplace environments can expose individuals to carcinogens, such as asbestos, silica, and heavy metals, which can increase the risk of developing lung cancer. According to the American Cancer Society, asbestos exposure alone is responsible for approximately 4% of all lung cancer cases in the United States.

3. Secondhand Smoke

While smoking is a well-established cause of lung cancer, exposure to secondhand smoke can also significantly elevate the risk for non-smokers. The World Health Organization (WHO) estimates that second-hand smoke causes an estimated 600 000 premature deaths a year, the majority (64%) among women. In the Eastern Mediterranean Region 38% of students aged 13–15 are exposed to second-hand smoke at home, and in many countries only around a quarter of homes are smoke-free. Only around 50% of schools ban the use of tobacco products by teachers.

4. Air Pollution

Prolonged exposure to air pollutants, including fine particulate matter (PM2.5), polycyclic aromatic hydrocarbons (PAHs), and other toxic substances in the air, has been associated with an increased risk of lung cancer. According to the Global Burden of Disease Study, air pollution is estimated to contribute to around 15% of lung cancer cases worldwide.

5. Genetic Factors

While genetics play a more significant role in some cancers than others, certain genetic factors can predispose individuals to lung cancer. People with a family history of the disease may have a higher risk. Additionally, genetic mutations, such as those in the EGFR gene, can increase susceptibility to lung cancer.

6. Lung Diseases

Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis, can raise the risk of developing lung cancer. According to the American Lung Association, people with COPD are at a higher risk of lung cancer, and lung cancer is often diagnosed at a more advanced stage in individuals with COPD.

7. Diet and Nutrition

While diet is not a direct cause of lung cancer, it can influence the risk of developing the disease. A study published in Cancer Epidemiology, Biomarkers & Prevention found that a diet low in fruits and vegetables and high in processed and red meats was associated with an increased risk of lung cancer.


Lung cancer is a complex disease with multiple risk factors, and smoking is just one piece of the puzzle. Understanding the various possible causes of lung cancer beyond smoking is crucial for prevention and early detection. By reducing exposure to environmental toxins, improving workplace safety, and making healthier lifestyle choices, individuals can take steps to lower their risk and promote better lung health. It is also vital to be aware of these risk factors and seek medical advice for proper screening and early intervention.

Dr.Sudip Shrestha
Founder & Executive Chairman Sr. Consultant Medical Oncologist Nepal Cancer Hospital & Research Center

Designation: Founder and Chairman, Senior Consultant Medical Oncologist

Qualification: MBBS, MD, Post Graduate Training in Medical Oncology

Department: Medical Oncology

Special interest: Chemotherapy, Immunotherapy, Targeted Therapy, Precision Medicine

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