The epidemiology series of brain-related disorders in Mongolia: nationwide registry-based epidemiological study on CNS tumours in Mongolia, 2015-2019.

No epidemiological study on central nervous system tumours is available for Mongolia. The aim of this study was to determine the incidence, mortality and survival of people diagnosed with central nervous system tumours in Mongolia. It reports cancer data for the entire population (3.3 million) during the period between 2015 and 2019. Data was obtained from the National Cancer Registry of Mongolia. Diagnosis of tumours was established according to the diagnostic criteria of the International Classification of Diseases-10 (ICD-10). Incidence and mortality rates were calculated as mean annual numbers per 100,000 population. Age-standardized incidence and age-standardized mortality rates were calculated from age-specific rates by weighting directly from the World Standard Population. The three-year survival from 2015 through 2017 was calculated between treatment types by the Kaplan-Meier survival analysis. It found 515 (adults: 83 %; children: 17%) newly diagnosed central nervous system tumour cases over the five year period. The national age-standardized incidence of central nervous system tumours for the entire population was 3.7 per 100,000. The rate was higher for males than females (4.2 versus 3.4 per 100,000, respectively). Only 23% of the diagnosed cases were confirmed histologically. The most common tumour was glioma (57.6% of histologically verified tumours). In children (age 0-19 years) the age-specified incidence rate of tumours was 1.4 per 100,000. Geographically, the age-standardized incidences of the Eastern region were higher than the country average rates for both genders. During the period, 381 deaths were registered with an age-standardized mortality rate of 3.0 per 100,000 population. Furthermore, the overall three-year survival rate was 40.6% (out of 283 patients, 115 survived). The five-year prevalence of tumours was 183 and the mean per 100,000 population was 5.5. In conclusion, the data from the National Cancer Registry indicate that the incidence and survival rates of central nervous system tumours in Mongolia are relatively low. The most common location of central nervous system tumours was the brain. Glioma was the most common tumour among histologically confirmed cases. Despite the limitations, data from this study should provide information for national health policy and health care assessment. To improve the diagnosis, prognosis and treatment of central nervous system tumours, expansion of the cancer registry through collecting data on non-malignant tumours, increasing the rate of histological verification, conducting studies on cancer epidemiology and the introduction of advanced treatment technologies for central nervous system tumours are recommended.