Trends in incidence of brain and central nervous system tumors in Norway, 1970-1999.

The aim of this study was to investigate trends in the incidence of childhood and adult brain and central nervous system (CNS) tumors in Norway from 1970 through 1999. In this period, a total of 14,641 patients were diagnosed with a primary benign or malignant neoplasm of the brain and CNS. Age-adjusted incidence rates were reported together with results of loglinear regression and an age-period-cohort model based on the Poisson regression model. In children (<15 years), the proportion of brain and CNS tumors was 28.2% (1,042/3,697) of all new cancer cases compared with 2.8% in adults (13,599/492,237). The overall rate of brain and CNS tumors increased during the study period from 6.49 to 12.02 cases per 100,000 person-years. A trend of leveling off in incidence of most tumor categories during the study period was indicated with a possible continuing increase in the period 1995-1999, especially in the age group 0-4 years and in patients aged 60 years or more. Age and period together provided a satisfactory model in patients being <60 years of age and less completeness of diagnosis was found in males compared with females, possibly due to the distribution in males of more aggressive tumors.