This publication defines cancer using the International Statistical Classification of Diseases, 10th Revision (ICD-10).
Adult cancer patients often die from causes unrelated to their cancer diagnosis. To show only the effect of cancer deaths on survival, adult survival estimates are net survival estimates. Net survival estimates compare the survival of cancer patients with that of the general population.
Childhood cancer survival estimates are overall survival estimates. Comparisons to the general population are not needed for childhood cancer patients. This is because death of a child within 10 years of a cancer diagnosis is almost always due to their cancer diagnosis.
The datasets present age-standardised estimates for adults by gender, stage and deprivation quintile and childhood cancer. Age-standardisation allows comparisons between population groups and over time. To age-standardise, the adult estimates use the International Cancer Survival Standard weightings with 5 age groups. The childhood estimates are age-standardised by giving equal weight to each age group (0 to 4, 5 to 9 and 10 to 14 years). All age groups must pass robustness tests to present an age-standardised estimate.
If estimates fail the quality tests for more than 2 of the 5 age groups or 2 non-adjacent age groups, it is not possible to present age-standardised estimates. If a single age group or 2 adjacent age groups fail the quality tests, a combined age group is formed with an adjacent age group. The combined age group is re-tested for statistical quality. If the statistical quality tests are now passed, an age-standardised estimate using 4 age groups may be presented.
Using net survival methods, survival greater than 100% can occur if the survival experience in cancer patients is greater than the survival experience of the general population. For example, a high proportion of breast cancers are screen-detected and women who attend screening have on average better health status, therefore are less likely to die from non-cancer causes than the general population.
The datasets also present confidence intervals at the 95% level. A confidence interval is a range of values that is used to quantify the imprecision in the estimate of an indicator. A wider confidence interval shows that the indicator value presented is likely to be a less precise estimate of the true underlying value.
The Cancer survival methodology documentation has more details on the methods used. A detailed impact paper of methodology changes for cancer survival accompanies this release.