Temporal trends in the incidence of malignant and non-malignant primary brain and central nervous system tumors by method of diagnosis in England, 1993-2017

Background Several studies report increasing incidence of primary CNS tumors. The reasons for this are unclear. Methods Data on all 188,340 individuals diagnosed with a primary CNS tumor in England (1993-2017) were obtained from the National Cancer Registry. Data on all CT head and MRI brain scans in England (2013-2017) were obtained from NHS Digital. Age-sex-standardized annual incidence rates per 100,000 population (ASR) were calculated by calendar year, tumor behavior, tumor location and method of diagnosis. Temporal trends were quantified using average annual percent change (AAPC). Results The ASR for all CNS tumors increased from 13.0 in 1993 to 18.6 in 2017 (AAPC: 1.5%, 95% CI: 1.3, 1.7). The ASR for malignant tumors (52% overall) remained stable (AAPC: +0.5%, 95% CI: -0.2, 1.3), while benign tumors (37% overall) increased (AAPC: +2.6%, 95% CI: 1.2, 4.0). Among the 66% of benign tumors that were microscopically confirmed, the ASR increased modestly (AAPC: 1.3%, 95% CI: 0.5, 2.1). However, among the 25% of benign tumors that were radiographically confirmed, the ASR increased substantially (AAPC: 10.2%, 95% CI: 7.9, 12.5), principally driven by large increases in those aged 65+. The rate of CT head scans in Accident & Emergency (A&E) increased during 2013-2017, with especially large increases in 65-84 and 85+ year olds (AAPCs: 18.4% and 22.5%). Conclusion Increases in CNS tumor incidence in England are largely attributable to greater detection of benign tumors. This could be the result of increasing use of neuroimaging, particularly CT head scans in A&E in people aged 65+