Tobacco smoke contains over 7,000 chemicals, with at least 70 known carcinogens such as benzo[a]pyrene, nitrosamines, and formaldehyde.
When smoking, these harmful substances can damage the DNA in lung cells, leading to gene mutations. These mutations may cause uncontrolled cell growth, eventually forming tumors.
The DNA damage caused by smoking accumulates over time. The longer the smoking duration and the greater the amount, the more damage accumulates, increasing the risk of lung cancer.
Smoking is associated with both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Small cell lung cancer is a more aggressive and faster-growing type of lung cancer, more common among smokers.
Research shows that smokers are 15-30 times more likely to develop lung cancer than non-smokers. After quitting smoking, the risk of lung cancer gradually decreases over time.
In addition to active smoking, passive smoking (inhaling second-hand smoke) also increases the risk of lung cancer.
Besides lung cancer, smoking is also associated with various other cancers (such as oral, laryngeal, esophageal, and pancreatic cancers), cardiovascular diseases, and chronic obstructive pulmonary disease (COPD).