Trends in the incidence of primary intracranial tumors in Osaka, Japan.

We analyzed the trends in the age-standardized incidence rates of 10,460 cases of primary intracranial tumors diagnosed during 1975 and 2004, Osaka, Japan using the Joinpoint regression analysis. During the period 1975-2004, the age-standardized incidence rates of total intracranial tumors increased until 1987 at 3.1% per year and then decreased significantly at -1.8% per year. The time trends were different according to the age groups. In the age group 0-19, the rate did not exhibit substantial increase or decrease. In the age group 20-74, the rates increased significantly until 1988 and then leveled off until 1999 and finally decreased. Whereas in the age group 75 and over, the rates increased drastically until 1984 and then leveled off. During the recent 10 year period 1995-2004, the age-standardized incidence rates of meningioma decreased significantly, but those of glioblastoma did not.