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.