| Summary: | Summary The aetiologic role of tobacco smoking was elucidated in a case-control study comprising 579 cases of male lung cancer registered during 1972-1977 in northern Sweden. The population aetiologic fraction attributable to smoking was about 80 % in this series. Pipe smoking was as common as cigarette smoking and gave similar relative risk. The pipe smoking cases, however, had significantly higher mean age and mean smoking years at the time of diagnosis than the cigarette smoking cases. An obvious dose-response relation was found for both cigarette and pipe smoking. In ex-smokers, the relative risk gradually decreased from five years after cessation of smoking. This decrease was, however, much less pronounced in ex-pipe smokers than in ex-cigarette smokers. High relative risks were obtained for small cell and squamous cell carcinomas. For adenocarcinomas the relative risk was considerably lower but still significantly increased. Two types of controls were used, i.e. deceased and living. Comparison with living controls gave generally higher risk estimates than comparison with deceased controls. In Sweden the mortality rate of lung cancer has more than doubled during the last 20 years and lung cancer is at present the most frequent cause of With the background death from cancer in males. of many epidemiologic findings published since the pioneer work in the UK and US (Doll & Hill, 1950,1952; Levin et al., 1950; Wynder & Graham, 1950) it seems likely that tobacco smoking is mainly responsible for this increase. The literature on smoking and lung cancer has been evaluated and reviewed in several recent comprehensive reports
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