Objective: To describe national trends in Norway in lung cancer incidence among young adults and its relationship to adolescent smoking.
Material and methods: Between 1954 and 1998, a total of 1108 non-carcinoid lung cancers in individuals aged 20-44 were reported to the Cancer Registry of Norway. Temporal variations were studied in age and sex-specific rates, in age-adjusted rates, and in cohort specific rates. The association between cancer incidence and smoking prevalence was evaluated.
Results: The incidence 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, the incidence rates converged among male and female young adults. The incidence at age 40-44 was highly correlated with smoking prevalence at age 15-19 in males (r = 0.88) and females (r = 0.82) within the same birth cohort.
Interpretation: The lung cancer incidence 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.