Adolescent smoking and trends in lung cancer incidence among young adults in Norway 1954-1998

Objective: To describe the national trends in lung cancer incidence among young adults and the relationship to adolescent smoking. Methods: Between 1954 and 1998, a total of 1108 non-carcinoid lung cancers were reported to the Cancer Registry of Norway in individuals aged 20-44 years. Temporal variations were studied in age and sex specific rates, in age-adjusted rates, and by means of age-period-cohort modelling. The association between cancer incidence and smoking prevalence was evaluated. Results: The lung cancer incidence rate among women aged 40-44 in Norway continued to increase into the most recent time interval (1994-1998) whereas the rate among men aged 40-44 was essentially constant after 1970. Consequently, lung cancer incidence rates converged among male and female young adults. Lung cancer incidence rates at age 40-44 were highly correlated with smoking prevalence at age 15-19 in males (r=0.88) and females (r=0.82) within the same birth cohort. Conclusions: The lung cancer incidence rate in young Norwegian women now equals that of men. The risk at age 40 44 was closely associated with teenage smoking, indicating that duration and age of onset are important.