Lung cancer develops when cells in the lungs grow uncontrollably, often forming tumors that interfere with breathing and other vital functions. The primary cause of lung cancer is smoking, responsible for nearly 85–90% of cases. Tobacco smoke contains carcinogenic chemicals that damage lung tissue and trigger abnormal cell growth over time. The risk increases with the number of cigarettes smoked and the duration of smoking.
Secondhand smoke is another significant risk, especially for non-smokers living with smokers. Even brief exposure can increase the risk of lung cancer.
Environmental exposures also play a role. Radon gas, a naturally occurring radioactive gas found in soil and buildings, is the second leading cause of lung cancer, particularly in non-smokers. Asbestos, once commonly used in construction, and long-term exposure to air pollution, diesel exhaust, and certain industrial chemicals can also elevate risk.
Genetics may influence susceptibility. Individuals with a family history of lung cancer have a higher risk, even if they’ve never smoked.
Other contributing factors include previous radiation therapy to the chest, chronic lung diseases like COPD, and older age, as risk tends to increase with time.
Understanding and minimizing these risks are essential steps in lung cancer prevention and early detection.