Trends in lung cancer incidence in Sweden with special reference to period and birth cohorts

Objective: Sweden has one of the largest population-based cancer registers in the world that provides an opportunity to examine the trend of lung cancer incidence during a 35-year period. The primary aim of the present study was to estimate the effects of birth cohort, year of diagnosis (period), and age on the time trends of lung cancer incidence rates, and to analyze the gender-specific incidence of different histopathological types of lung cancer. Results: Among men the age-standardized incidence rate increased steadily up to 1982, when a peak of 49 cases per 100,000 person-years was reached. Among women the incidence rate was lower and showed a monotonic increase throughout the observation period. The fastest rate of increase was noted among the youngest women. In women, but not in men, there was a steady increase in risk with each successive birth cohort. For both sexes there were large changes in the histopathological distributions of cases. The most notable was a major increase in adenocarcinomas. Conclusions: The overall age-adjusted incidence rate of lung cancer in Sweden has stabilized in men during the past two decades while rates are still increasing in women. In view of the continued high prevalence of smoking among young women, a future definite increase in the overall number of lung cancer cases in women can be expected.