Temporal trends in incidence of primary brain tumours in the Australian Capital Territory and New South Wales 2000 to 2008

Abstract

There are conflicting reports from Europe and North America regarding trends in the incidence of primary brain tumour, whereas the incidence of primary brain tumours in Australia is currently unknown. We aimed to determine primary brain tumour incidence in Australia with age-, sex-, and benign-versus-malignant histology-specific analyses. A multicenter study was performed in the state of New South Wales (NSW) and the Australian Capital Territory (ACT), representing a combined population of >7 million with >97% rate of population retention for medical care. We retrospectively sourced pathology databases servicing neurosurgical centres in NSW and ACT for histologically confirmed primary brain tumours diagnosed from January 2000 through December 2008. Data were weighted for patient outflow and data completeness. Incidence rates were age standardised and trends analysed using joinpoint analysis. A weighted total of 7651 primary brain tumours were analysed. The overall US-standardised incidence of primary brain tumours was 11.3 cases 100000 person-years (+0.13; 95% confidence interval, 9.8-12.3) during the study period with no significant linear increase. A significant increase in primary malignant brain tumours from 2000 to 2008 was observed; this appears to be largely due to an increase in malignant tumour incidence in the {u2265}65-year age group. A significant increasing incidence in glioblastoma multiforme (GBM) was observed in the study period (annual percentage change, 2.5; 95% confidence interval, 0.4-4.6, n=2275), particularly after 2006. In GBM patients in the {u2265}65-year group, significantly increasing incidence for men and women combined (APC, 3.0; 95% CI, 0.5-5.6) and men only (APC, 2.9; 95% CI, 0.1-5.8) were seen. Rising trends in incidence were also seen in meningioma for total male population (APC, 5.3; 95% CI, 2.6-8.1, n=515) and males aged 20-64 years (APC, 6.3; 95% CI, 3.8-8.8). Significantly decreasing incidence trends were observed for Schwannoma for the total study population (APC, -3.5; 95% CI, -7.2 - -0.2, n=492), significant in women (APC, -5.3; 95% CI, - 9.9 - -0.5) but not men. This collection represents the best estimate of primary brain tumour incidence in Australia. Whether the observed increase in malignant primary brain tumours, particularly in persons aged {u2265}65 years, is due to improved detection, diagnosis, and care delivery or a true change in incidence remains undetermined. An important trend observed from this study, using benign tumour data collection, was an increasing trend in meningioma and a decreasing trend in Schwannoma in the years 2000 to 2008. This is data for which we have no direct comparison in Australia. Our registries may observe an increase in malignant tumours in the next few years that they are not detecting now due to late ascertainment. We recommend a direct, uniform and centralized approach to monitoring primary brain tumour incidence, including the introduction of non-malignant tumour data collection. Show more