**Methods**

This page provides information on the statistics used on this website. Statistics are not reported separately for rare subtypes where the number of cases is too small to make reliable estimates but will be included in the total figures reported for their overarching diagnostic group.

**Incidence**

Incidence is the number of new cases of disease that occur within a defined population during a specified time period, usually a year. Age (5-year age bands) and sex-specific rates are calculated and rates are expressed as per 100,000 persons per year.

**Sex rate ratio**

The sex rate ratio (male:female) is the annual incidence of males divided by the annual incidence of females.

**Expected UK cases per year**

The expected number of UK cases per year is estimated by applying HMRN's age and sex-specific annual incidence rates to equivalent UK population age and sex strata (2016 mid-year population of the region obtained from the Office for National Statistics).

**Age standardised rates**

Direct age standardisation is used to allow comparisons to be made between HMRN’s annual incidence rates and those of other populations with different age and sex structures. HMRN's age and sex-specific annual incidence rates are applied to the equivalent 2013 European Standard Population strata. The age standardised rate is then calculated by dividing the total number of cancers that would have occured in the standard population if it had experienced the same incidence rates as HMRN, by the total standard population.

Rates weighted to other Standards including the World Standard Population (2000-2025) are coming soon.

**Survival**

Survival is often expressed as the proportion of patients still alive at a specified time after their condition was diagnosed, for example 1 or 5 years. Overall survival includes deaths from any causes, not just the disease of interest. Relative survival, the statistic used on this website, uses English life tables (obtained from the Office for National Statistics) to calculate survival in the absence of other causes of death providing an estimate that shows the difference the cancer is making.

Relative survival is calculated by dividing the proportion of patients with the disease who are still alive at the end of a defined time period (i.e. 1, 3 or 5 years) by the proportion of people in the general population of the same sex and age who are still alive at the end of the same period.

HMRN cases newly diagnosed from 2004-2016 are included in the calculation of relative survival, and it is estimated for 1, 3 or 5 years after diagnosis using the Stata programme strel developed by the London School of Hygiene & Tropical Medicine Cancer Survival Group.

Survival estimates cannot be reliably estimated when the number of deaths is small. Where this occurs, these are marked as 'undefined' in the downloadable data.

## Prevalence

Prevalence measures the number (or proportion) of people with a condition at a specific time. Cancer prevalence estimates generally include all people who have ever had the disease, regardless of whether or not they have been cured.

HMRN uses limited-duration prevalence, which is defined as the number of people alive on a certain day who were diagnosed with the disease at any point during a specified time period. The time periods used on this website are 1 year, 3 years, 5 years and 10 years before the index date (currently 31/08/2016). These time periods are relevant to different stages in the patient pathway. For example, for potentially curable conditions, 1 and 3-year prevalence gives an indication of the number of patients undergoing intensive treatment and/or monitoring; whereas 10-year prevalence contains people on treatment, those living with cancer, and those who have been cured.

**Estimated UK prevalence**

The expected number of prevalent UK cases is estimated by applying HMRN's age and sex-specific prevalence rates to equivalent UK population age and sex strata.