National Bowel Cancer Screening Program monitoring report 2025

Bowel cancer may be present for many years before a person shows symptoms, such as visible rectal bleeding, change in bowel habit, bowel obstruction, or anaemia. Often, symptoms such as these are not exhibited until the cancer has reached a relatively advanced stage. However, non-visible bleeding of the bowel may occur in the precancerous stages (Figure 1.1) for some time. The relatively slow development of most bowel cancers means that precancerous polyps and adenomas, and early-stage cancers, can potentially be screened for and treated. This makes bowel cancer a valid candidate for population screening (Standing Committee on Screening 2018).

An immunochemical faecal occult blood test (iFOBT) is a common method of bowel cancer screening (Schreuders et al. 2015). An iFOBT is a non-invasive test that can detect microscopic amounts of blood in a sample from a bowel motion, which may indicate a bowel abnormality, such as an adenoma or cancer.

National Bowel Cancer Screening Program

In Australia, government-funded, population-based bowel cancer screening has been available through the NBCSP since 2006. The NBCSP is managed by the Department of Health, Disability and Ageing and delivered through the National Cancer Screening Register (NCSR, November 2019 to present) with support from state and territory governments. The NBCSP aims to reduce the incidence of, and illness and mortality related to, bowel cancer in Australia through screening to detect cancers and pre-cancerous lesions in their early stages, when treatment will be most successful.

The Clinical practice guidelines for the prevention, early detection and management of colorectal cancer were endorsed by the National Health and Medical Research Council in 2017 (CCACCGWP 2017). The rollout of the recommended biennial iFOBT screening target age group was completed in 2020. Eligible Australians are able to screen every 2 years using a free iFOBT screening kit.

Target population

The target population list is compiled from those registered as an Australian citizen or permanent migrant in the Medicare enrolment file or registered with a Department of Veterans’ Affairs gold card.

The population screening chapter of the guidelines was revised in 2023 to recommend that biennial iFOBT screening for the asymptomatic Australian population be offered from age 45 and continue to age 74 (previously 50–74) (CCACCSWP 2023). From 1 July 2024, eligible people aged 45–49 can request their first NBCSP kit from the program, or their doctor. This change to the program did not occur within the time period for reporting against performance indicators in this report. See Kit requests for those aged 45–49, July to December 2024.

Table 1.2 outlines the starting dates of each phase of the NBCSP and the target age groups.

(a)  Eligible birth dates, and thus invitations, ended on 31 December 2010.

(b)  Ongoing NBCSP funding commenced.

(c)  People aged 45 to 49 can request their first bowel cancer screening kit. People aged 50 to 74 continue to receive a bowel cancer screening kit every 2 years.

Note: The eligible population for all Phase 2 and 3 start dates incorporates those turning the target ages from 1 January of that year, onwards.

To participate in the NBCSP, invitees complete the screening test and post it to the NBCSP pathology laboratory for analysis. Results are sent to the participant, to the participant’s nominated primary health-care practitioner (PHCP), and to the NCSR. Participants with a positive screening result, indicated by blood in the stool sample, are advised to consult their PHCP to discuss further diagnostic assessment – in most cases, a colonoscopy.

The AIHW conducted a study of people diagnosed with bowel cancer between 2006 and 2008. This study showed that NBCSP invitees (particularly those participating) who had been diagnosed with bowel cancer had a lower risk of dying from the disease and were more likely to have less advanced bowel cancers when diagnosed than non-invitees. These findings show that the NBCSP is contributing to reducing morbidity and mortality from bowel cancer in Australia (AIHW 2014a). More recent AIHW data linkage projects have further supported these findings (AIHW 2018a, 2018b).

For more information on the NBCSP, see the Department of Health, Disability and Ageing website.

Monitoring the NBCSP

NBCSP participant data come from a variety of sources along the screening pathway. Data are collected electronically, as well as from forms that participants, PHCPs, colonoscopists, pathologists, and other medical staff complete and return to the NCSR. While health service organisations providing colonoscopy services are required to implement the Colonoscopy Clinical Care Standard (ACSQHC 2020), which includes reporting NBCSP patient results to the NCSR, form return from health practitioners is not mandated by the NBCSP, therefore these data may be incomplete.

This report is the tenth to present national data for the NBCSP, using the current key performance indicators (PIs) developed by the National Bowel Cancer Screening Program Report and Indicator Working Group (Table 1). These indicators were endorsed by the Standing Committee on Screening, the Community Care and Population Health Principal Committee, the National Health Information Standards and Statistics Committee, and the National Health Information and Performance Principal Committee. They are consistent with the 5 Australian Population Based Screening Framework steps: recruitment, screening, assessment, diagnosis, and outcomes (AIHW 2014b).

Current reporting limitations

Except for participation and iFOBT results, the completion and sending of other NBCSP forms or data by health practitioners is required in accordance with Australian Commission on Safety and Quality in Health Care standards (ACSQHC 2020), but is not mandated by the NBCSP. Therefore data – and results – for PIs 3 to 9 are not complete. In this report, for the second time, colonoscopy form and MBS claim data have been supplemented with Participant follow-up function (PFUF) data for those who had a positive screening test. See Improvements to the known colonoscopy count in Appendix A for further details.

Other limitations of NBCSP data include the lack of reliable population subgroup identification at the time of invitation. Within the 2022–2023 reporting period, NBCSP participants can self-identify as being an Aboriginal and/or Torres Strait Islander person, having a disability, or speaking a language other than English at home by completing and returning the participant details form along with their iFOBT for analysis. The NCSR uses self-reporting from the participant details form and the Medicare Voluntary Indigenous Identifier, along with other sources such as the National Cervical Screening Program (for invitees who participate in cervical screening) to assign Indigenous status. These sources are still not currently sufficient to reliably identify membership of these subgroups for all invitees. Hence, it is not possible to accurately determine NBCSP participation rates for these subgroups due to the lack of denominators (invitations issued). Ways to reduce these limitations are constantly being investigated; Equity in the NBCSP gives estimates of participation for these subgroups using proportions from the 2021 Census.

In this report, for the first time, NBCSP records have been matched to cancer incidence data to 2021. Therefore, PI 6a (bowel cancer detection rate), PI 6b (PPV of diagnostic assessment for detecting bowel cancer), and PI 7 (interval cancer rate) are reported.   

Four performance indicators remain aspirational, in that there is either a lack of national data or incomplete data. In this report, PI 5a (adenoma detection rate), PI 5b (positive predictive value, or PPV, of diagnostic assessment for detecting adenoma are not formally reported due to incomplete data. These indicators require complete data return from histopathology. Additionally, PI 8 (cancer clinico-pathological stage distribution) requires national cancer staging data, which is not currently available. Lastly, PI 9 (adverse events – hospital admission) requires linkage with complete national hospital admissions data, which is not currently performed. However, the NCSR currently has (incomplete) information on adverse events, and this will be used until a more complete adverse event data source becomes available.

Invitations to the target age group exclude those who do not have a valid mailing address in the NCSR. These individuals cannot be mailed, or may not receive, their NBCSP invitation until their Medicare address is updated. All users of Medicare are encouraged to update their address details when they move residence.

This is the fifth NBCSP monitoring report to use data extracted from the NCSR. The NCSR is a live database which is updated over time and later reports using data for the same time period may have a greater level of completeness.