Data sources, calculations and notes

The following information relates to the data shown on the Cancer type summaries for NSW and the Cancer Statistics NSW module.

Data sources

Aboriginal cancer incidence and mortality

Data are sourced from the NSW Cancer Registry from within the Master Linked Dataset and uses an Enhanced Reporting Algorithm (ERA) to identify Aboriginal people (population data are sourced from SAPHaRI, Centre for Epidemiology and Evidence, NSW Ministry of Health and are based on the Australian Bureau of Statistics 2016 Census).

The ERA uses linked data from multiple datasets (the NSW Cancer Registry, NSW Admitted Patient Data Collection, NSW Emergency Department Data Collection and the Australian Coordinating Register Cause of Death Unit Record File) to improve the completeness of identification of Aboriginal people in the NSW Cancer Registry Incidence and Mortality Dataset.[1, 2] Enhancement increased the number of cases reported among Aboriginal people by a third, with impacts varying by cancer type, age group and other demographic factors.[3]

BreastScreen

BreastScreen Information System, BreastScreen NSW (population data are sourced from SAPHaRI, Centre for Epidemiology and Evidence, NSW Ministry of Health and are based on the Australian Bureau of Statistics 2021 Census (including populations for Aboriginal people)).

Cancer incidence and mortality

Data are sourced from the NSW Cancer Registry (population data are sourced from SAPHaRI, Centre for Epidemiology and Evidence, NSW Ministry of Health and the Australian Bureau of Statistics 2016 Census).

Projected cancer incidence and mortality

Data are sourced from the NSW Cancer Registry. Population data are sourced from NSW Department of Planning and Environment population projections.

Relative survival

Data are sourced from the NSW Cancer Registry with mortality followed up from linked death data from NSW Registry of Births, Deaths and Marriages and National Death Index.

Data calculations

Cancer incidence and mortality

For more information on age-standardised rate, cancer incidence, cancer mortality, risk or 10-year trend calculations, refer to Appendix 4 of Cancer in NSW: Incidence and Mortality report 2010.

Projected cancer incidence and mortality

Cancer incidence and mortality projections are a mathematical extrapolation of past trends. They assume that the most recent trend will continue into the future, and are intended to illustrate future changes that might reasonably be expected to occur if the stated assumptions were to apply over the projection period.

The nature of the projection method used and inherent fluctuations in both cancer incidence and mortality trends and population dynamics mean that care should be taken when using and interpreting the projections presented.

Specifically, the projections are not forecasts and do not attempt to allow for changes which may affect future cancer incidence and mortality rates, including changes in risk factors and early detection methods.

Relative survival

One-year and five-year age-standardised relative survival were estimated for adults (aged 15 to 100 years) diagnosed with cancer. Estimates were age-standardised using the International Cancer Survival Standard (ICSS) weights. Relative survival is a measure of the survival of people with cancer compared with survival of the general population. It is a standard approach used by cancer registries to report population-level survival statistics. However, there are different methodologies used to calculate relative survival which mean the results may not be comparable to survival data reported in other jurisdictions.  

The cohort approach was used to estimate relative survival for people diagnosed during 1997-2001, 2002–2006 and 2007–2011. The period approach was used to estimate relative survival for people diagnosed 2012–2016. 

Notes

BreastScreen

Breast screening participation rates shown here are expected to differ from figures of Health and Welfare for the same period, due to variations in the population projections used in the denominator. The participation rates presented here are based on the number of women who live in NSW and are screened in NSW. Interstate clients have been excluded.

 

Source(s):

1. Australian Institute of Health and Welfare, Australian Bureau of Statistics. National best practice guidelines for data linkage activities relating to Aboriginal and Torres Strait Islander people. AIHW Cat. No. IHW 74. Canberra: AIHW; 2012.

2. Population and Public Health Division. Improved reporting of Aboriginal and Torres Strait Islander peoples on population datasets in New South Wales using record linkage - a feasibility study. Sydney: NSW Ministry of Health 2012.

3. Tervonen HE, Purdie S, Creighton N. Using data linkage to enhance the reporting of cancer outcomes of Aboriginal and Torres Strait Islander people in NSW, Australia. BMC Medical Research Methodology, 2019;19:245. doi: org/10.1186/s12874-019-0884-8.