Incidence of intracranial meningiomas in Denmark, Finland, Norway and Sweden, 1968-1997.

ABSTRACT

It has been reported that the incidence of meningioma increased in several industrialized countries in the late 1970s and early 1980s. The aim of this study was to evaluate the time trends in incidence of meningiomas in Denmark, Finland, Norway and Sweden, with emphasis on the age distribution and sex ratio. Information about cases of meningiomas in people aged 15-84 years was obtained from the cancer registries of these Nordic countries for the years 1968-1997, and estimates of person-years at risk were calculated from information provided by the national population registries. Age-specific incidence rates per 100,000 and incidence rate ratios were calculated for 3-year periods. The femalemale ratios were also evaluated. The combined incidence among men increased from 1.4 to 1.9 per 100,000 during the follow-up period, the corresponding rates for women were 2.6 and 4.5. The femalemale ratio increased over time for several age groups and was as high as 3.51 in the group aged 40-44 years in the latest follow-up period (1993-1997). In summary, our results provide some support for the idea that the introduction of computed tomography in the late 1970s has had an impact on the detection of cases in people aged 60 and over. The decrease in the rate or detection postmortem has affected the incidence time trend, but it also coincides with widespread use of new imaging technologies. The increasing trend shown for the femalemale ratio in the group aged 35-59 years is consistent with the possibility that increasing use of hormones may affect the incidence of meningiomas in women.