Background
Global rates of brain and central nervous system (CNS) tumours vary greatly (1). In Switzerland, standardised incidence rates were 7.8 per 100’000 in men and 5.1 per 100’000 in women in 2013 to 2017 (2). Many studies only include malignant brain and CNS tumours due to a lack of available data regarding benign/borderline tumours. In the Cancer Registry Zurich, Zug, Schaffhausen and Schwyz in Switzerland, data on both malignant and benign/borderline brain and CNS tumours have been registered for the Canton of Zurich since 1980.
 
Objectives
The aim of this study was to analyse trends in incidence, mortality, and 5-year relative survival of malignant and benign/borderline brain and CNS tumours between 1980 and 2021 in the Canton of Zurich, Switzerland, stratified by sex, age group, behaviour, and histological subtypes.
 
Methods
We used incidence data from the Cancer Registry of Zurich, Zug, Schaffhausen and Schwyz including primary benign/borderline and malignant tumours diagnosed between 1980 and 2021 in the Canton of Zurich in patients aged ≥15 years (N=10,226). The tumours were classified into subgroups based on histology codes using the definitions in the CBTRUS Statistical Report (3). Mortality data were based on the national cause of death statistics (N=3514). We calculated age-standardised incidence and mortality rates per 100,000 person-years and used Joinpoint to analyse trends. The cohort approach was used to estimate 5-year relative survival. Expected survival was calculated based on the Ederer II method (4).
 
Results
The age-standardised incidence rate of malignant tumours was stable over time (around 7.7-8.2 per 100,000 person-years in men and 4.6-5.2 in women), while the rate of benign/borderline tumours increased from 3.8 in 1980-1990 to 10.8 in 2011-2021 in men and from 5.7 to 19.1 in women. Incidence rates as well as the increasing trend were generally higher in the middle age groups. The highest incidence rates were observed for neuroepithelial tumours in men and for tumours of the meninges in women. The age-standardised mortality rate remained stable over time for malignant tumours (around 5.5-6.1 in men and 3.5-4.0 in women) but significantly decreased for benign/borderline tumours (from 1.0 in 1980-1990 to 0.5 in 2011-2021 in men and from 1.2 to 0.5 in women). Age-standardised 5-year relative survival increased from around 80% in 1980-1990 up to >90% in 2011-2017 for benign/borderline tumours and from <20% to around 30% for malignant tumours. There was a small survival advantage in women compared to men.
 
Conclusions
While the incidence and mortality rates remained stable for malignant brain and CNS tumours in the Canton of Zurich between 1980 and 2021, we observed an increase in incidence and a decrease in mortality rates for benign/borderline tumours. Five-year relative survival improved over time for both benign/borderline and malignant tumours. The increasing incidence rates in benign/borderline tumours may be due to improved diagnostic techniques and an increasing use of CT scans, as reported in Switzerland (5) and other countries (6). The increase in relative survival may reflect improved detection and treatment.

References