Cigarette smoking: causes most cases of lung cancer

Cigarette smoking: causes most cases of lung cancer; relative risk of smokers vs. nonsmokers is 10:1; increases to 20:1 for >40 cigarettes/day; risk is strongly related to number of cigarettes smoked, described in pack years (number of packs per day x number of years smoking)

Also associated with carcinomas of lip, tongue, pharynx, larynx, esophagus, bladder, pancreas, kidney, floor of mouth

10% of smokers have atypia or hyperplasia of bronchial epithelium

Carcinogens in tobacco smoke are benzo [a] pyrene (an initiator) and phenol derivatives (promoters)

Usually associated with squamous cell and small cell carcinoma, less likely with adenocarcinoma

Other causes: radiation exposure, uranium (RR with uranium exposure is 4:1 for nonsmokers, 10:1 for smokers vs. general population); a*****estos (RR with a*****estos exposure is 5:1 for nonsmokers, 50-90:1 for smokers vs. general population), exposure to nickel, chromate, coal, mustard gas, arsenic, beryllium, iron, vinyl chloride, radon radiation, gold miners

Causes of death for a*****estos workers are: 20% lung cancer, 10% mesothelioma, 10% GI carcinomas