Australia has one of the highest rates of colorectal cancer in the world and is the third most commonly diagnosed cancer among Aboriginal and Torres Strait Islander people (after lung cancer and breast cancer). Several risk factors have been identified which may contribute to bowel cancer.1 These risk factors include, modified risks i.e., excess body fat, physical inactivity, poor diet (e.g. high consumption of processed meats), high alcohol consumption and smoking, as well as risk such as family history and genetic susceptibility, and exposure to ionising radiation.1
Australia commenced an organised program of colorectal (bowel) cancer population screening in 2006, the National Bowel Cancer Screening Program (NBCSP). Indicators of the performance of this Program include the proportion of positive FOBT cases having a follow-up diagnostic assessment (colonoscopy), and the elapsed time between a positive FOBT and the assessment.1 It is desirable that follow-up diagnostic assessments occur in a timely manner, thus minimising potential harms from delayed diagnosis and treatment.1 This indicator should not be considered a hospital wait time indicator, as there are various steps, decisions and wait times in the pathway between a positive screen and a diagnostic assessment.
It should be noted that the reporting of colonoscopies to the NBCSP is not mandatory and there is an unknown degree of under-reporting that may affect the data. The data shown in this analysis are based on information recorded in the Program Register only. Caution is advised when using this data as it may not reflect the true population.
About this measure
Between 2010 and 2014, 840 new cases of colorectal cancer were diagnosed in Aboriginal and Torres Strait Islander peoples, and between 2014 and 2018, 531 new cases were reported corresponding to an age-standardized rate of 116.9 per 100,000 Aboriginal and Torres Strait Islander people. The age standardized mortality rate in Aboriginal and Torres Strait Islander peoples in the period 2016-2020 was 35.5 per 100,000 people.3
Australia has one of the highest rates of colorectal cancer in the world, with this cancer projected to be the fourth most common cancer recorded by cancer registries in Australia in 2021 (after breast cancer, prostate cancer and melanoma of the skin). Bowel cancer was the third most common cancer reported to Australian cancer registries in 2018. It is estimated that it would be the fourth most common cancer reported in 2022.3-4
Bowel cancer may be present for many years before showing symptoms, such as visible rectal bleeding, a change in bowel habit, bowel obstruction or anaemia. Often these symptoms do not occur until the cancer has reached a relatively advanced stage. However, non-visible bleeding of the bowel may occur in the precancerous stages at an earlier time. The relatively slow development of bowel cancer means that precancerous polyps and adenomas, and early-stage cancers, can potentially be screen-detected and treated effectively.3
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 taken from a bowel motion. This may indicate a bowel abnormality, such as an adenoma or cancer. FOBT screening reduces the risk of mortality from colorectal cancer.5-7 A positive FOBT result requires a follow-up procedure to determine an accurate diagnosis. Colonoscopy is currently considered the most accurate procedure, because it enables biopsy and subsequent histopathological diagnosis. Colonoscopy also allows identification and endoscopic removal of polyps and adenomas.
Current status
In 2020, 14,296 Aboriginal and Torres Strait Islander peoples in the target age range provided a valid FOBT screening test, of whom 1418 (9.9%) were positive. This was a higher percentage than the national screening positive rate of 7.0%.3
Colonoscopy follow-up after a positive colorectal screening test
In 2020, 51.1% of Aboriginal and Torres Strait Islander people who had a positive FOBT screening kit had a follow-up colonoscopy recorded within 360 days.3
Time between positive screening test and diagnostic assessment
In 2020, Aboriginal and Torres Strait Islander Australians had a longer median time between a positive screen and assessment (64 days) compared with the national median time (49 days).3
Trends
Colonoscopy follow-up after a positive colorectal screening test
From 2014 to 2020, the colonoscopy follow-up rate within 360 days decreased among Aboriginal and Torres Strait Islander people from 58.5% to 51.1%%.3
It should be noted that the reporting of colonoscopies to the NBCSP is not mandatory and that there is an unknown degree of under-reporting that would affect the data. In November 2019, the NBCSP Register data were transitioned from the NBCSP Register, maintained by Services Australia (formerly the Department of Human Services), to the National Cancer Screening Register (NCSR), maintained by Telstra Health. The NCSR is a live database updated over time such that later reports using these data achieve a greater level of completeness.3
Time between positive colorectal screening test and diagnostic assessment
From 2014 to 2020, there was a general decreasing trend in the median time between a positive FOBT screen and a colonoscopy assessment for Aboriginal and Torres Strait Islander people from 83 days in 2014 to 64 days in 2020.
Addressing barriers to screening
To increase Aboriginal and Torres Strait Islander participation rates, the Australian Government Department of Health and Aged Care funded the Menzies School of Health Research in 2018-2019 to develop the National Indigenous Bowel Screening Pilot. The pilot ran for 12 months from 1 November 2018 to 31 October 2019. In this pilot, an alternative screening pathway was used whereby primary health care centres promoted the NBCSP to their eligible Indigenous patients, distributed the NBCSP screening kits, and supported patients to participate in bowel screening. Health centres were also given flexibility to incorporate bowel screening into their practices to suit their local circumstances and were encouraged to embed NBCSP bowel screening as routine practice. Screening participation through this alternative pathway (39.8%) was reported to be significantly higher than for Aboriginal and Torres Strait Islander people using the usual pathway (23.3%).8
About the data
Follow-up after a positive FOBT screening test
This measure shows the proportion of the eligible invited population returning a positive (abnormal) result from a correctly completed FOBT screening test, who had a follow-up diagnostic assessment (colonoscopy).
Numerator: Number of persons who had a follow-up colonoscopy within 360 days.
Denominator: Number of persons who had a positive FOBT result in the defined 12-month period
Median time
This measure shows the median time between a positive NBCSP screening test and a follow-up diagnostic assessment.
Median time to follow-up assessment data were first reported in 2016, following publication of NBCSP performance indicators in 2014.
References
Activity in this area
Data
Australian Institute of Health and Welfare 2022. National Bowel Cancer Screening Program: monitoring report 2022. Cat. no. CAN 148. Canberra: AIHW. Accessed March 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2022/summary
Policy
Australian Government. Department of Health and Aged Care. National Bowel Cancer Screening Program – Policy Framework. Accessed March 2023; https://www.health.gov.au/our-work/national-bowel-cancer-screening-program
Australian Government. Department of Health and Aged Care. The National Indigenous Bowel Screening Program: Accessed March 2023; https://www.health.gov.au/our-work/national-indigenous-bowel-screening-pilot#:~:text=This%20pilot%20program%20aimed%20to,participating%20in%20the%20pilot%20program
Data caveats
The NBCSP program began in 2006, offering screening to people aged 55 and 65 years, and subsequently was extended to include other ages. In 2014, the Australian Government announced that the program would be extended to offer free 2-yearly screening for all Australians aged 50–74 years. The extension was completed in 2020.1 As reporting of colonoscopies to the NBCSP is not mandatory, there is an unknown degree of under-reporting that may affect the data. These data are based on information recorded in the Program Register only.
There are limitations in the data available to estimate Indigenous Australians’ participation in the NBCSP, due to differences in the ‘not stated’ proportions between the 2019–2020 NBCSP participation data and the 2016 Census data (3.0% and 6.2% ‘not stated’, respectively). An overall participation rate for invitees who self-identified as Indigenous has been estimated, but these limitations should be considered when interpreting these data.3
References
- Australian Institute of Health and Welfare. Regional Insights for Indigenous communities. Life expectancy and mortality. Accessed March 2023; https://www.rific.gov.au/Topics/Life-expectancy-mortality/Causes-death
- Australian Institute of Health and Welfare. National Indigenous Australian Agency. Health status and outcome. Accessed March 2023; https://www.indigenoushpf.gov.au/measures/1-08-cancer#:~:text=In%20the%205%2Dyear%20period,cancer%20(765%20or%208%25)
- Australian Institute of Health and Welfare 2022. National Bowel Cancer Screening program monitoring report 2022. Cat. no. CAN 148. Canberra: AIHW. Accessed March 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2022/summary
- Cancer Australia 2022. Bowel cancer statistics. Cancer Australia 2022. Accessed March 2023; https://www.canceraustralia.gov.au/cancer-types/bowel-cancer/statistics#:~:text=In%202020%2C%20bowel%20cancer%20was,2%2C847%20males%20and%202%2C507%20females
- Hewitson P et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008 Jun;103(6):1541-9. doi: 10.1111/j.1572-0241.2008.01875.x.
- Australian Institute of Health and Welfare 2018. Analysis of bowel cancer outcomes for the National Bowel Cancer Screening Program. Cat. no. CAN 113. Canberra: AIHW. Accessed March 23; https://www.aihw.gov.au/reports/cancer-screening/analysis-of-bowel-cancer-outcomes-nbcsp-2018/summary
- Cole SR et al. 2013. Shift to earlier stage at diagnosis as a consequence of the National Bowel Cancer Screening Program. Medical Journal of Australia 198:327–330.
- Australian Government of Health and Aged Care. Final report on the National Indigenous Bowel Screening Pilot. Accessed March 2023; https://www.health.gov.au/resources/publications/final-report-on-the-national-indigenous-bowel-screening-pilot?language=en