Unit of analysis:
The unadjusted crude proportion of cancer cases for which stage data are available for cases with a principal diagnosis of:
*The top 5 incident cancers that were eligible for staging comprise breast (female) cancer (ICD-10 code C50), colorectal cancer excluding appendix (C18.0, C18.2–C20), lung cancer excluding trachea (C34), melanoma of the skin excluding skin of genitals (C43) and prostate cancer (C61). Certain morphology codes that were not eligible for staging are excluded, such as sarcomas, lymphomas or carcinoid tumours.
**Colon cancer (C18) excludes cancer of the appendix (C18.1)
***Excludes melanoma of “unknown primary site”
Numerator: Incident cancer cases for a selected RD-Stage at diagnosis value (stage 1, stage 2, stage 3, stage 4, or unknown) for a selected cancer type.
Denominator: All eligible RD-Stage records that were able to be matched to an incident cancer case in the ACD for the relevant cancer type. The denominator includes cases with an "Unknown" stage at diagnosis for which the registry did not have sufficient information to derive stage.
RD-Stage at diagnosis is defined as the best estimate of summary TNM stage of diagnosis as derived by cancer registries from data sources available to them. These data will be used for statistical purposes as opposed to clinical management and supporting individual patient care. Clinical requirements for prognostic precision differ from epidemiological requirements for comparability and statistical completeness.2 Specifically, the collection of RD-Stage:
- Is intended for epidemiological population-based analyses only – in particular, this information stage at diagnosis will assist in understanding the severity of disease across tumour types and different and sociodemographic groups as well as inform us of patterns of incidence and mortality.
The Business Rules have been tested and reviewed by all states and territories to ensure applicability across all Australian population based cancer registries. The Business Rules have also been endorsed as a national standard for the collection of stage data by the AACR.
Australian Cancer Database3
Cancer incidence indicates the number of new cancers diagnosed during a specified time period (usually one year). The major source of national cancer incidence data is the ACD which contains records of all primary, malignant cancers (except basal cell and squamous cell carcinomas of the skin) diagnosed in Australia since 1982.
All Australian states and territories have legislation that makes cancer a notifiable disease. Various designated bodies, i.e., institutions such as hospitals, pathology laboratories and registries of births, deaths and marriages, are required to report cancer cases and deaths to their jurisdictional cancer registries.
Each registry supplies incidence data annually to the AIHW under an agreement between the registries and the AIHW. These data are compiled into the ACD, the only repository of national cancer incidence data.
Linkage of RD-Stage and the ACD
The data used for reporting this measure have been created by linkage of data from RD-Stage collection and the ACD. These data are therefore limited to records that have been matched across these two collections. For this analysis, 3.7% records in the RD-Stage collection (approximately 2,500 out of 72,200 cases) have been excluded from these analyses for the following reasons:
- RD-stage record did not link to the ACD.
- The RD-Stage record linked to an ACD record that was out of scope.
- RD-Stage record was ineligible for stage (such as sarcomas, lymphomas or carcinoid tumours)
- RD-Stage record was a duplicate
A relatively small number of records (approximately 600, less than 1%) records in the ACD were in scope but did not link to the RD-Stage collection. These records did not link because:
- They had been altered since being submitted to the ACD and were now out of scope; or
- Applied to melanomas of unknown primary site but not coded as such in the ACD; or
- Had been staged at a point after diagnosis but not at diagnosis.
International data on stage at diagnosis – England and Canada
Data presented for the international comparisons of stage at diagnosis have been sourced from the Canadian Partnership Against Cancer (Canada) and the National Cancer Intelligence Network (England). Data for Australia and England are available at the national level. For Canada, data are not available for Quebec. Further information on the scope, and methodology for collection, and relevant caveats are available through the links under the ‘References’ tab.
The Canadian data are presented in greater detail than the Australian and English data, the following changes have been made to the publicly available Canadian data for ease of comparison:
- Stage 0 cancers have been excluded from totals and proportions;
- Sub-stages (e.g. Stage IA, Stage IIB) have been aggregated to Stage 1, Stage 2, Stage 3 and Stage 4, accordingly.
- For lung cancer, small cell and non-small cell lung cancers have been grouped. Small cell lung cancers represented 13% of staged lung cancers in Canada.
- Cases where stage data were “not available” have been combined with “Unknown” stage.
- This analysis presents crude proportions that have not been adjusted.
- Collection of these data has provided an insight into differences in the availability, extent and accessibility of information that is required to derive RD-Stage across Population-based Cancer Registries (PBCRs). Notably, the availability and quality of data accessible to PBCRs was found to improve during the study period.
- Remoteness area of the patient's usual place of residence was defined using the ABS Australian Statistical Geography Standard (ASGS) remoteness structure classification, 2011. The process for calculating remoteness areas results in some records being split across areas, e.g. a record might be 0.6 Major Cities and 0.4 Inner Regional. The number of incident cases by remoteness, expressed as decimals and aggregated for split records, has been rounded to the nearest whole number. Totals may differ from other demographic breakdowns due to rounding.
- Socioeconomic group of the patient's usual place of residence defined using the ABS SEIFA Index of Relative Socioeconomic Disadvantage, 2011.
- Due to the small number of incident cancer cases in a single year (2011), results of analysis by Indigenous status should be interpreted with caution.
- Analyses by Indigenous status are only available in this report for New South Wales, Victoria, Queensland, Western Australia and Northern Territory, where higher completeness of reporting Indigenous status has been determined by the AIHW in past analyses.