[Tobacco and cancer of the lung. A case-control study]

The relationship between cigarette smoking and risk of lung cancer has been analyzed in a case control study of 98 cancer patients and 108 age matched healthy controls. This relationship has been studied based on age when smoking started, number of cigarettes per day and minimum number of cigarettes smoked, and smoke inhalation. The excess rate (ER) of lung cancer amongst those who started smoking before age 20 was 3.47 (C.I. 95% 1.33 + 9.05) above those who started smoking later. There is a progressive increase in ER as the mean daily number of cigarettes and the minimum number of cigarettes smoked increase. The ER in those who inhale smoke was 2.4 (C.I. 95% 1.6 - 5.05) when compared to those who did not inhale smoke. It is essential to quantify the magnitude of the smoking habit as well as its duration since these variables are going to determine the risk of acquiring the disease. Case control smoking-lung cancer study.