Why is **smoking** strongly linked to lung cancer (carcinogenic risk far above other organs)?
ALungs are exposed first to inhaled carcinogens (e.g. benzo[a]pyrene from tobacco tar) that directly damage epithelial DNA; chronic irritation also promotes mutations
BLungs lack any DNA repair
CCigarette smoke is radioactive only
DLungs have no immune response
Answer & Solution
Correct answer: A. Lungs are exposed first to inhaled carcinogens (e.g. benzo[a]pyrene from tobacco tar) that directly damage epithelial DNA; chronic irritation also promotes mutations
Tobacco smoke contains 70+ known carcinogens (e.g., benzo[a]pyrene, nitrosamines, formaldehyde). PAHs form DNA adducts → mutations in TP53, KRAS → loss of cell-cycle control → cancer. Squamous cell carcinoma of bronchi is the classic 'smoker's lung cancer'. Also linked: oral, oesophageal, bladder, kidney cancers.
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