Increasing brain cancer rates in Canada.

OBJECTIVE

To analyse brain cancer patterns in Canada, particularly according to age and sex distributions, temporal patterns and regional variations. Changes in diagnostic techniques, survival rates and trends by tumour type were also examined.

DESIGN

Descriptive epidemiologic study based on Canada-wide population data for 1959-88.

OUTCOME MEASURES

Rates of death, incidence and admission to hospital because of brain cancer, as well as survival time and methods of diagnosis.

SUBJECTS

Incidence and death rates and time trends were examined for Canada as a whole, by province and by census division.

RESULTS

The rates of death from brain cancer increased rapidly among Canadians aged 55 years or more from 1959 to 1988. In particular, age-adjusted death rates increased by 117%, 797% and 118% among men 65 to 74 years, 75 to 84 and 85 or more respectively. The corresponding increases among women were 138%, 535% and 400%. The incidence rates also increased substantially. The trends in incidence rates by tumour type indicated that the increase was more pronounced for glioblastomas. The incidence rates of cases detected histologically, radiologically and clinically all increased.

CONCLUSIONS

Because glioblastomas are generally easier to diagnose than astrocytomas and because the incidence rates of glioblastomas were found to increase substantially, the increased brain cancer rates among elderly people may not be entirely attributable to improved diagnostic techniques. However, analytic investigations of the impact of changes in diagnostic procedures on brain cancer trends are needed to clarify this issue.