Geographical variation in malignant and benign/borderline brain and CNS tumor incidence: a comparison between a high-income and a middle-income country.

PURPOSE: There is large variability in reported incidence rates of primary brain/CNS tumors across the world, with mostly higher rates in higher-income countries. The aim was to compare malignant and benign brain/CNS tumor incidence between Zurich (Switzerland), a high-income country, and Georgia, a lower middle-income country. METHODS: For the period March 2009 to February 2012, we extracted the following tumors based on topography according to ICD-O3: C70.0-C72.9, and C75.1 (pituitary gland). Data were categorized into histology groups based on the WHO 2007 histological classification. Age-standardized rates per 100,000 person-years were calculated by subgroups. RESULTS: We included 1104 and 1476 cases of primary brain/CNS tumors for Zurich and Georgia, respectively. Mean age of patients was significantly lower in Georgia compared to Zurich (50.0 versus 58.3 years). Overall age-standardized incidence rates for malignant and benign brain/CNS tumors were 10.5 (95% CI 9.9-11.0) for Georgia and 23.3 (95% CI 21.9-24.7) for Zurich with a ratio of benign to malignant tumors of 1.656 for Georgia and 1.946 for Zurich. The most frequent histology types were meningiomas in both regions, followed by glioblastomas in Zurich, but pituitary tumors in Georgia. CONCLUSION: Age-adjusted incidence rates of brain/CNS tumors were considerably higher in Zurich compared to Georgia, both for benign and malignant tumors, which is in line with other studies reporting higher rates in high-income than in low- and middle-income countries. The frequency distribution may be related to differences in diagnosing techniques and the population age structure.

Incidence rates of the primary brain tumours in Georgia--a population-based study.

BACKGROUND: To determine the incidence rate and to describe other basic epidemiological data of primary brain tumours in a population-based study in Georgia, performed between March 2009 and March 2011. METHODS: Active case ascertainment was used to identify brain tumour cases by searching neuroradiology scan reports and medical records from all participating medical institutions, covering almost 100% of the neurooncology patients in the country. RESULTS: A total of 980 new cases were identified during the two-year period. For a population of almost 4.5 million, the overall annual incidence rate was 10.62 per 100,000 person-years, age-standardized to the year 2000 US population (ASR). Non-malignant tumours constituted about 65.5% of all tumours. Males accounted for 44% and females for 56% of the cases. Among classified tumours, age-standardized incidence rates by histology were highest for meningiomas (2.65/100,000), pituitary adenoma (1.23/100,000) and glioblastomas (0.51/100,000). ASR were higher among females than males for all primary brain tumours (10.35 vs. 9.48/100,000) as well as for main histology groups except for neuroepithelial, lymphomas and germ cell tumours. CONCLUSIONS: The annual incidence rate of all primary brain tumours in Georgia, though comparable with some European registry data, is low in comparison with the 2004-2005 Central Brain Tumor Registry of the United States (CBTRUS) database, which may reflect variations in reporting and methodology. The higher percentage of unclassified tumours (37.8%) probably also affects the discrepancies between our and CBTRUS findings. However, the most frequently reported tumour was meningioma with a significant predominance in females, which is consistent with CBTRUS data.