Cancer data in Australia

Australian Cancer Database 2020

All forms of cancer, except basal and squamous cell carcinomas of the skin, are notifiable diseases in each Australian state and territory. This means there is legislation in each jurisdiction that requires hospitals, pathology laboratories and various other institutions to report all cases of cancer to their central cancer registry.

An agreed subset of the data collected by these cancer registries is supplied annually to the AIHW, where it is compiled into the Australian Cancer Database (ACD). The 2020 version of the ACD used in this report contains data on all cases of cancer diagnosed from 1982 to 2020 for all states and territories.

Cancer reporting and registration is a dynamic process, and records in the state and territory cancer registries may be modified if new information is received. As a result, the number of cancer cases reported by the AIHW for any particular year may change slightly over time and may not always align with state and territory reporting for that same year. Further details about the 2020 ACD can be found in the Data Quality Statement.

Classification of country/region of birth

Within the ACD, the Standard Australian Classification of Countries (SACC), 2016 is used to identify the country of birth and to group countries into regions of birth (ABS 2016). 

The SACC provides guidelines for consistent collection, aggregation and dissemination of statistics by country. The Australian Bureau of Statistics (ABS) endorses the use of this classification when collecting, aggregating and disseminating data relating to characteristics such as birthplace and country of residence.

The country names within the SACC reflect country titles recognised by the Australian Government. The ABS monitors changes in the official recognition of country titles by the Australian Government and updates the SACC as necessary to ensure the classification remains current. The identification of countries and country groups within the SACC does not imply the expression of any opinion on the part of the ABS or AIHW regarding the legal status of any country, territory, or area, or concerning the delimitation of its frontiers or boundaries.

Missing data

COB data is not available for all cases recorded in the ACD. COB is recorded as either ‘Not stated’ or ‘Inadequately described’ in 9.1% of records between 2006 and 2020. The proportion of missing data varies by cancer type.

Melanoma of the skin had a comparatively high proportion (25.7%) of records where COB was missing, which, given the high incidence of melanoma in Australia, also impacts the rate of not stated for all cancers combined. The impact of the comparatively high rate of missing data for melanoma is discussed further in the section on melanoma of the skin.

Missing COB was also relatively high for chronic lymphocytic leukaemia (20.1%), and myeloproliferative neoplasms (excluding CML) (17.3%), chronic myeloid leukaemia (CML) (15.3%), testicular cancer (11.1%), thyroid cancer (11.1%) and non-Hodgkin lymphoma (10.3%).

For all other cancer types, the proportion of not stated COB was less than 10% and ranged from 1.8% for mesothelioma and 2.3% for pancreatic cancer to 9.9% for cervical cancer.

Missing COB data has increased over time, with 12.9% of cases (all cancers combined) recording not stated in the most recent period (2016–2020). The reason for this increase is uncertain.

One possible explanation for the varying rates of missing COB is the type of notifications used to register a case of cancer in a state or territory cancer registry, and whether that notification (especially if only a single diagnostic pathology report) contains COB information.

In the case of melanoma, skin cancer clinics, dermatologists and general practitioners in Australia are all capable of performing a procedure generating a tissue sample for pathology, but not necessarily mandated to notify cancer depending on their state or territory cancer registry Policy Directive. In this case, the cancer registry notification will be a pathology report, which does not include COB.

Similarly, missing COB for certain haematological conditions could similarly be explained by the expanding sources of notifications available to state and territory cancer registries for haematological cancer. In particular, cytogenetics, molecular studies and flow cytometry performed on blood samples taken outside a notifying facility from a patient on surveillance only.

Table B.1 provides a table of missing COB data by cancer type, by time-period for the period 2006 to 2020.

Why isn’t cancer incidence available for all countries or regions of birth?

Cancer incidence is reported only for the countries or regions of birth with a population that had, on average, at least 20,000 people living in Australia per year between 2006 to 2020. Where a country of birth has a smaller population than this, it is not published because of the increased risk of misleading cancer incidence rates that more commonly appear with smaller populations.

For data quality purposes, the combined COB of Serbia and Montenegro is used within this report rather than the COB of Serbia and the separate COB of Montenegro. 

In addition, this report only discusses rates for countries or regions of birth for which there were 20 or more cases diagnosed in the period 2006–2020 and was in the leading 20 cancers. The accompanying data Excel workbook in the data section and data visualisation includes counts of the leading 20 cancers and incidence rates where there are 10 or more cases (and for the 2006–2010, 2011–2015, 2016–2020 and 2006–2020 periods).

Source: Australian Cancer Database 2020

Notes: 

1. Rates are only published where the cancer is in the leading 20 cancers for at least one COB or ROB within the period for persons. 
2. Rates are not published for cancers where the cancer is not a leading cancer for any COB/ROB for persons within the relevant period’ (denoted n.p.).