We have estimated that at least 102,000 children and adults are currently living with a brain tumour in the UK. This is how we came to that number...
Cancer prevalence statistics are essential for public health decisions and advocating change, but there are few reliable brain tumour prevalence estimates as they are hard to calculate, particularly as cancer registry data has historically not been collected for low grade tumours in the UK. However, the Central Brain Tumor Registry of the United States (CBTRUS), a full (mandated) registry, published a study in 2010 estimating that brain tumour prevalence in the US was 688,000. We have used this study to extrapolate an equivalent estimate for the UK of 102,000, comparing this with Public Health England's prevalence estimate for England to assess validity of the estimate (adjusted for the UK). On the basis that the estimates were similar, but the UK National Cancer Registry data in 2010 was less reliable and consistent in comparison to the US data, we have chosen to use the 102,000 estimate.
This estimate of 102,000 was based on US prevalence rate estimate of 221.8 per 100,000 for brain tumours and other central nervous system tumours (across all types, grades and patient ages), at the end of 2010. This rate was adjusted to reflect current reported UK incidence and survival rates, resulting in a UK prevalence rate estimate of 157.5 per 100,000 at the end of 2010 which, when applied to the Office of National Statistics mid-year UK population estimates for 2014, gave the estimate of 102,000. CNS tumours were also included in the study data but, as they represent just 3% of the overall incidence in the UK 2, we have not identified them separately in our key message.
The reasonability of this estimate was checked using Public Health England's 2013 prevalence estimate of 55,000 for England (excluding London and the South East), adjusted by scaling to the UK population and by applying a PHE finding about the proportion of people living with brain tumours in the UK that come from England. The result was close to the 102,000 and gave us assurance on the validity of our estimate.
US survival data has been assumed to be similar to the UK, as the patterns of incidence and survival have historically been similar overall (but not at a detailed level) for both countries. There is no published 5 year survival rate in the UK at present for low grade tumours so the US rate has been assumed.
This should not to be relied upon as a precise figure but an estimate of overall prevalence, based on the best data currently available, and validated by a separate set of data. Use of this estimate for detailed analysis (by grade, type, age group etc) should not be relied upon, due to the assumptions made above.
 Porter KR, McCarthy BJ, Freels S, Kim Y, Davis FG. Prevalence estimates for primary brain tumors in the United States by age, gender, behavior, and histology. Neuro Oncol. 2010;12(6):520-527.