National Bowel Cancer Screening Program monitoring report 2026

International Classification of Diseases for Oncology

Cancers were originally classified solely under the International Classification of Diseases and Related Health Problems (ICD) classification system, based on topographic site and behaviour. However, during the creation of the 9th Revision of the ICD in the late 1960s, working parties suggested creating a separate classification for cancers that included improved morphological information. The first edition of the International Classification of Diseases for Oncology (ICD-O) was subsequently released in 1976 and, in this classification, cancers were coded by both morphology (histology type and behaviour) and topography (site).

Since that first edition of the ICD-O, a number of revisions have been made, mainly in the area of lymphomas and leukaemias. The current edition, the 3rd Edition (ICD-O-3), was released in 2000 and is used by most state and territory cancer registries in Australia, as well as by the AIHW in regard to the ACD.

Index of Relative Socio-economic Disadvantage

The Index of Relative Socio-economic Disadvantage (IRSD) is one of 4 Socio-Economic Indexes for Areas developed by the ABS. This index is based on factors such as average household income, education levels, and unemployment rates. It is not a person-based measure, but an area-based measure of socioeconomic disadvantage in which small areas of Australia are classified on a continuum from disadvantaged to affluent. This information is used as a proxy for the socioeconomic disadvantage of people living in those areas and may not be correct for each person in that area.

In this report, the first socioeconomic area corresponds to geographical areas containing the 20% of the population with the greatest socioeconomic disadvantage according to the IRSD, and the fifth area corresponds to the 20% of the population with the least socioeconomic disadvantage. Caution should always be used when analysing the results of data that have been converted using correspondences, with the potential limitations of the data considered.

Socioeconomic areas for screening data

Participants’ areas of residence were assigned to socioeconomic areas using the Statistical Area Level 2 of the participant’s residential address according to the IRSD for 2021. Socioeconomic groupings (based on IRSD rankings) were calculated with a Statistical Area Level 2 correspondence, using a population‑based method at the Australia‑wide level. Participants whose Statistical Area Level 2 was not available in the socioeconomic correspondence were included in an ‘Unknown’ column in the relevant tables.

Socioeconomic areas for incidence and mortality

Socioeconomic disadvantage areas were assigned to cancer cases according to the IRSD for 2021 of the Statistical Area Level 2 of residence at the time of diagnosis, and to deaths according to the 2021 Statistical Area Level 2 of residence at the time of death.  

International Statistical Classification of Diseases and Related Health Problems

The ICD is used to classify diseases and other health problems (including symptoms and injuries) in clinical and administrative records. The use of a standard classification system enables the storage and retrieval of diagnostic information for clinical and epidemiological purposes that is comparable between different service providers, across countries and over time.

In 1903, Australia adopted the ICD to classify causes of death and it was fully phased in by 1906. Since 1906, the ICD has been revised 9 times in recognition of new diseases (for example, acquired immunodeficiency syndrome, or AIDS), increased knowledge of diseases, and changing terminology in describing diseases. The version currently in use, the ICD‑10 (WHO 1992), was endorsed by the 43rd World Health Assembly in May 1990 and officially came into use in World Health Organization member states from 1994.

International Statistical Classification of Diseases and Related Health Problems, Australian Modification

The Australian modification of the ICD-10, referred to as the ICD-10-AM (NCCH 2010), is based on the ICD-10. The ICD-10 was modified for the Australian setting by the National Centre for Classification in Health, with assistance from clinicians and clinical coders. Despite the modifications, compatibility with the ICD-10 at the higher levels of the classification (that is, up to 4-character codes) has been maintained. The ICD-10-AM has been used to classify diagnoses in hospital records in all states and territories since 1999–2000 (AIHW 2000).

Remoteness Areas

The Remoteness Areas divide Australia for statistical purposes into broad geographical regions that share common characteristics of remoteness. The Remoteness Structure divides each state and territory into several regions on the basis of their relative access to services. There are 6 classes of Remoteness Area in the Remoteness Structure: Major cities, Inner regional, Outer regional, Remote, Very remote, and Migratory. The category Major cities includes Australia’s capital cities, except for Hobart and Darwin, which are classified as Inner regional. Remoteness Areas are based on the Accessibility and Remoteness Index of Australia, produced by the Australian Population and Migration Research Centre at the University of Adelaide.

Remoteness Area for screening data

Participants’ residential address Statistical Area Level 2 data were mapped to 2021 Australian Statistical Geography. As some Statistical Area Level 2 areas can span different Remoteness Areas, a weighting for each Remoteness Area was attributed to the Statistical Area Level 2 in such cases. This can result in non‑integer counts for remoteness classifications.

Remoteness Area for incidence and mortality

Each unit record in the ACD contains 2021 Statistical Area Level 2. To calculate cancer incidence by Remoteness Area, a correspondence was used to map the 2021 Statistical Area Level 2 to the 2021 Remoteness Area. Cancer mortality rates by Remoteness Area were based on 2021 Remoteness Area classifications.

Tables in this report based on geographical location were rounded to integer values. Where figures were rounded, discrepancies may occur between totals and sums of the component items. Participants whose postcode was not available in the remoteness correspondence were included in an ‘Unknown’ column in the relevant tables.