Relationship of lung cancer and cigarette smokers in Northern Thailand (The study compares smoking and non smoking groups).

The incidence of lung cancer in smoker with a habit up to 20 year duration was found to be 29 times higher among the smokers. Smoker of not more than 20 years have a 9 times greater risk of contracting lung cancer than nonsmoker. Smoker with a habit of 21-40 year duration have a 30 times greater risk of lung cancer than the nonsmoker, (if smoking over 41-46 year duration, the risk of lung cancer will increase to 47 times). Smokers with a habit of over 41 year duration will have a 47 times greater risk. In conclusion the higher incidence of lung cancer is closely related to the duration of smoking.