The primary risk factor for NSCLC is tobacco smoking, responsible for about 85% of all lung cancer cases. Other significant risk factors include exposure to secondhand smoke, radon gas, asbestos, and other environmental pollutants. Genetic predisposition also plays a role, with certain genetic mutations increasing the likelihood of developing NSCLC. Additionally, individuals with a history of chronic lung diseases like chronic obstructive pulmonary disease (COPD) are at higher risk.