The National Bowel Cancer Screening Program (NBCSP) commenced in 2006 with the aim of reducing morbidity and mortality from bowel cancer. Screening is directed at the eligible target population for cancer prevention and early detection. Indicators of the NBCSP performance include, among cases positive faecal occult blood tests (FOBT), the proportion who have a follow-up diagnostic assessment (colonoscopy) and the elapsed time between the positive FOBT and this assessment. It is important that follow-up diagnostic assessments occur in a timely manner, to avoid harms from delayed diagnosis and treatment. The data presented in this measure indicate the proportion of the eligible population having a follow-up colonoscopy recorded within 360 days of a positive FOBT result.
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 which is updated over time such that later reports using these data have a greater level of completeness.1
In the 2023 National Bowel Cancer Screening report1, for the first 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; hence, the trend data prior to 2021 cannot be compared with newer time periods.
About this measure
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 present until the cancer has reached a relatively advanced stage. However, non-visible bleeding of the bowel may occur in the precancerous stages for some time. The relatively slow development of bowel cancer means that precancerous polyps and adenomas, and early-stage cancers, can potentially be screen-detected and effectively treated.1
An immunochemical faecal occult blood test (iFOBT) is a common method of bowel cancer screening. 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. FOBT screening reduces the risk of CRC mortality.4
The two-yearly screening of the NBCSP was only fully rolled out from 2020 with phases in the preceding roll-out and target population shown below: 1
| Phase | Start date | End date | Target ages (years) |
|---|---|---|---|
| 1 | 7 August 2006 | 30 June 2008 | 55 and 65 |
| 2 | 1 July 2008 | 30 June 2011(a) | 50, 55 and 65 |
| 2(b) | 1 July 2011 | 30 June 2013 | 50, 55 and 65 |
| 3 | 1 July 2013 | Ongoing | 50, 55, 60 and 65 |
| 4 | 1 January 2015 | 50, 55, 60, 65, 70 and 74 | |
| 4 | 1 January 2016 | 50, 55, 60, 64, 65, 70, 72 and 74 | |
| 4 | 1 January 2017 | 50, 54, 55, 58, 60, 64, 68, 70, 72 and 74 | |
| 4 | 1 January 2018 | 50, 54, 58, 60, 62, 64, 66, 68, 70, 72 and 74 | |
| 4 | 1 January 2019 | 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72 and 74 |
(a) Eligible birth dates, and thus invitations, ended on 31 December 2010.
(b) Ongoing NBCSP funding commenced.
Note: The eligible population for all Phase 2 and 3 start dates incorporates all those turning the target ages from 1January of that year onwards.
A positive FOBT result requires a follow-up procedure to gain an accurate diagnosis. Colonoscopy is currently considered the most accurate follow-up procedure because it enables a biopsy and subsequent histopathological diagnosis. Colonoscopy also allows identification and endoscopic removal of precancerous polyps and adenomas.
Current status
In 2021, 85.5% of the eligible invited population (65,766 people) who returned a positive (abnormal) result from a correctly completed FOBT screening kit, had a follow-up colonoscopy recorded within 360 days of their screening result.
Rates were slightly higher among females (87.3%) than males (84.2%), and somewhat higher among younger persons, with the highest percentage applying to ages 50–54 years at 86.7% than among older persons, where the lowest percentage was for ages 70–74 years at 83.7%.1 This pattern was essentially the same in the males (85.7% vs 82.4%) and females (88.1% vs 85.3%).
Aboriginal and Torres Strait Islander peoples
In 2021, the colonoscopy follow-up rate within 360 days was lower among Aboriginal and Torres Strait Islander peoples (76.5%) than among their non-Indigenous counterparts (86.1%).1
Remoteness and socioeconomic status (SES)
In 2021, the follow-up colonoscopy rate was the lowest for participants living in Remote and Very remote areas (82.6 and 82.3%, respectively), followed by those in Outer regional areas (84.9%). Participants in the Inner regional areas had the highest follow-up rate (86.7%).
The follow-up diagnostic assessment rates increased with level of socioeconomic status from the lowest for participants living in the lowest socioeconomic areas (81.5%), and 85.9% in the third lowest socioeconomic areas, to the highest for those living in the highest socioeconomic areas (89.6%).1
International
Comparable international data for colonoscopy follow-up rates are not available, due to differences in screening processes and target populations internationally.
Trends
Monitoring reports before 2016 used a different methodology to analyse the diagnostic assessment rate. So, trend comparisons with rates published in earlier reports cannot be made. To allow trends to be compared over time, the new indicator specifications have been applied retrospectively to earlier years of the program data. From 2007 to 2011, the follow-up diagnostic assessment rate plateaued then decreased from 77.5% in 2011 to 61.8% in 2020. In 2021, this rate was 85.5%.
Differences in form-return and varying pathway practices for diagnostic assessment between years may have contributed to this outcome.1 Similar trends were observed for both sexes in the same period from 2007 to 2018, whereas since then, a decrease occurred in males and an increased in females.
Changes in the reporting process for follow-up colonoscopies, as well as changes in diagnostic assessment pathway practices between years, may be factors contributing to this observed overall decrease. It should also be noted that this indicator relies on information being reported to the Program Register; however, this is not mandatory, leading to incomplete data. Furthermore, the changes in data source from the NBCSP Register to the NCSR since 2019, which is updated over time, may give more complete estimates (reflected in increases for some estimates in 2020 compared with 2019).1 Furthermore, from 2021, participant follow-up function (PFUF) data are now used to supplement missing colonoscopy form data and MBS claims for those who had a positive screening test.1 This means data from 2021 onwards cannot be compared with previous years.
Aboriginal and Torres Strait Islander peoples
From 2014 to 2020, the colonoscopy follow-up rate within 360 days decreased among Aboriginal and Torres Strait Islander peoples from 58.5% to 51.1%. This rate was 76.5% in 2021.
Remoteness and socioeconomic status (SES)
From 2014 to 2020, the colonoscopy follow-up rate within 360 days decreased across all socioeconomic status areas with the largest decrease occurring in the lowest socioeconomic areas (SES1) from 66.8% to 52.7%.
From 2015 to 2020, the colonoscopy follow-up rate decreased across all remoteness areas, the largest of which was for Very remote areas, where the decrease was from 54.2% in 2015 to 43.4% in 2020.
Colorectal cancer control in Australia
Since the initial demonstration (pilot) projects for national colorectal cancer screening, and the subsequent years of implementation of the NBCSP, improvements have been observed in mortality and survival outcomes. The age-standardised colorectal cancer mortality rate decreased per 100,000 persons from 22.6 deaths in 2006 to 17.3 in 2018 and was estimated at 15.4 deaths per 100,000 in 2022.6 Between the periods 2004-2008 and 2014–2018, the 5-year relative survival from bowel cancer for people aged 50–74 years diagnosis rose from 64.8% to 70.6%.5 As reported in the Australian Cancer Database 2019, this survival rate also increased from 52.1% in 1985-1989 to 74.7% in 2015-2019.1
Data linkage studies have indicated that, compared with bowel cancers in people who were never invited to screen, screen-detected bowel cancers were associated with a 59% lower risk of death from bowel cancer. People diagnosed with screen-detected bowel cancers were less likely to die, and those who did die were less likely to die from bowel cancer, than applying to people whose bowel cancer was not screen-detected (note: 65.8% of deaths in people diagnosed with a screen-detected bowel cancer were due to bowel cancer, compared with a corresponding 78.1% in people never-invited to screen). Even after adjustment for lead-time bias, people whose bowel cancer was detected through the NBCSP had a 40% lower risk of dying from bowel cancer than individuals whose bowel cancer was diagnosed in the absence of an invitation to screen.6
Higher survival from screen-detected bowel cancers is likely to be due to cancer diagnosis at an earlier stage. Both the AIHW report7 and a recent study evaluating the NBCSP in South Australia8 found that screen-detected bowel cancers were more likely to be diagnosed at an earlier stage (as rated by degree of spread and reported metastases).
The proportion of people diagnosed with a localised (least advanced) bowel cancer was 30.0% for NBCSP invitees compared with 27.9% for those who were never invited to participate in the NBCSP between 2006 and 2010.7
In general, bowel cancers detected through the NBCSP experience higher survival outcomes. Modelling indicates that the NBCSP will prevent 92,200 cancers and 59,000 deaths over the period 2015–2040 with the current participation rate of 40%, but with potential to save 83,800 lives over this period if screening coverage can be increased to 60%. The NBCSP has been found to be cost-effective due to the cancer treatment costs averted.9
In 2018–2019, the Australian Government Department of Health and Aged Care funded the Menzies School of Health Research 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 participation 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 the flexibility to incorporate bowel screening into their practice to suit their local circumstances and were encouraged to embed NBCSP bowel screening in routine practice. Screening participation through this alternative pathway (39.8%) was reported to be significantly higher than for Indigenous people using the usual pathway (23.3%).10
About the data
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.
Remoteness
Participants were allocated to a remoteness area using the residential postcode supplied at the time of screening and the Australian Statistical Geography Standard (ASGS). For 2018 -2020 data, the 2016 ASGS was used; whereas for earlier years, the 2011 ASGS was used.
Socioeconomic status
Participants were allocated to a socioeconomic group using their residential postcode according to the Socio-Economic Indexes for Areas (SEIFA) Index of Relative Socio-Economic Disadvantage (IRSD). Data from 2017 onwards used the 2016 IRSD; for earlier years, the 2011 IRSD was used.
Aboriginal and Torres Strait Islander peoples
The final estimated resident Aboriginal and Torres Strait Islander population as at 30 June 2016 was 19% larger than the estimated population as at 30 June 2011 (ABS 2018). The ABS notes that the population increase is greater than demographic factors alone can explain. As well, the 2016 estimated population was 7% larger than the 2016 projected population based on the 2011 Census.
The extent of the increase in the Indigenous population estimates between 2011 and 2016 means that any rates calculated with Indigenous population estimates based on the 2016 Census will be artificially lower than those based on the 2011 Census and should not be compared with rates calculated using populations based on previous Censuses.1
Data caveats:
Monitoring reports before 2016 used a different methodology to analyse the diagnostic assessment rate. Therefore, to allow trends to be compared over time, the new indicator specifications have been applied retrospectively to earlier years of program data.
The NBCSP program began in 2006, offering screening to people aged 55 and 65 years, with this being subsequently 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. 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 NCSR, maintained by Telstra Health. The NCSR is a live database which is updated over time and later reports using these data may have a greater level of completeness.
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. However, from 2021, Participant follow-up function (PFUF) data are now used to supplement missing colonoscopy form data and MBS claims for those who had positive screening test.1 Hence, trend data prior to 2021 cannot be compared. More information on PFUF can be found in reference. 1
The performance indicators in the 2023 National Bowel Cancer Screening report1 use data collected for the NCSR (January 2020 to December 2023). However, this report also summarizes trends from 2007–2008 to 2020–2021 in program participation rate, diagnostic assessment rate, and time between positive screen and diagnostic assessment. These trends use data collected for the NBCSP Register as well as data collected for the NCSR.
Data sources:
Australian Institute of Health and Welfare 2023. National Bowel Cancer Screening Program: monitoring report 2022. Cat. no. CAN 154. Canberra: AIHW. Accessed June 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2023/data
Australian Institute of Health and Welfare 2022. National Bowel Cancer Screening Program: monitoring report 2022. Cat. no. CAN 148. Canberra: AIHW.
Australian Institute of Health and Welfare 2023. Cancer screening programs: quarterly data. Cat. no. CAN 114. Canberra: AIHW. Accessed June 2023; https://www.aihw.gov.au/reports/cancer-screening/national-cancer-screening-programs-participation/contents/about
Australian Institute of Health and Welfare 2021. National Bowel Cancer Screening Program: monitoring report 2021. Cat. no. CAN 139. Canberra: AIHW.
Australian Institute of Health and Welfare 2020. National Bowel Cancer Screening Program: monitoring report 2020. Cat. no. CAN 133. Canberra: AIHW.
Australian Institute of Health and Welfare 2019. National Bowel Cancer Screening Program: monitoring report 2019. Cat. no. CAN 125. Canberra: AIHW.
Australian Institute of Health and Welfare 2018. National Bowel Cancer Screening Program: monitoring report 2018. Cat. no. CAN 112. Canberra: AIHW.
Australian Institute of Health and Welfare 2017. National Bowel Cancer Screening Program: monitoring report 2017. Cat. no. CAN 103. Canberra: AIHW.
Australian Institute of Health and Welfare 2016. National Bowel Cancer Screening Program: monitoring report 2016. Cat. no. CAN 97. Canberra: AIHW.
References
Activity in this area
Data:
Australian Institute of Health and Welfare 2023. National Bowel Cancer Screening Program: monitoring report 2022. Cat. no. CAN 154. Canberra: AIHW. Accessed June 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2023/data
Australian Institute of Health and Welfare 2022. National Bowel Cancer Screening Program: monitoring report 2023. Cat. no. CAN 148. Canberra: AIHW. Accessed June 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2022/summary
Australian Institute of Health and Welfare 2023. Cancer screening programs: quarterly data. Cat. no. CAN 114. Canberra: AIHW. Accessed May 2023; https://www.aihw.gov.au/reports/cancer-screening/national-cancer-screening-programs-participation/contents/about
Policy:
Australian Government Department of Health. National Bowel Cancer Screening Program Policy Framework. Accessed June 2023; http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/program-frameworks-and-strategies
References
- Australian Institute of Health and Welfare 2023. National Bowel Cancer Screening Program: monitoring report 2023. Cat. no. CAN 154. Canberra: AIHW. Accessed June 2023; https://www.aihw.gov.au/reports/cancer-screening/nbcsp-monitoring-2023/summary
- Cancer Australia 2022. Bowel cancer statistics. Cancer Australia 2022. Accessed June 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
- Australian Institute of Health and Welfare 2022. Cancer Data in Australia. Cancer rankings data visualisation. Accessed June 2023; https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/contents/cancer-rankings-data-visualisation
- Hewitson P et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008 June;103(6):1541-9. doi: 10.1111/j.1572-0241.2008.01875.x.
- Australian Institute of Health and Welfare 2022. Cancer Data in Australia. Cancer survival data visualisation. Accessed June 2023; https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/contents/cancer-survival-data-visualisation
- Australian Institute of Health and Welfare 2018. Analysis of cancer outcomes and screening behaviour for national cancer screening programs in Australia. Cat. no. CAN 115. Canberra: AIHW. Accessed June 23; https://www.aihw.gov.au/reports/cancer-screening/cancer-outcomes-screening-behaviour-programs/summary
- 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 June 23; https://www.aihw.gov.au/reports/cancer-screening/analysis-of-bowel-cancer-outcomes-nbcsp-2018/summary
- Cole SR, Tucker GR, Osborne JM, et al. Shift to earlier stage at diagnosis as a consequence of the National Bowel Cancer Screening Program. Med J Aust. 2013 Apr 1;198(6):327-30. doi: 10.5694/mja12.11357.
- Lew JB, St John DJB, Xu XM, et al. Long-term evaluation of benefits, harms, and cost-effectiveness of the National Bowel Cancer Screening Program in Australia: a modelling study. Lancet Public Health 2:e331–e340.
- Australian Government of Health and Aged Care. Final report on the National Indigenous Bowel Screening Pilot. Accessed June 2023; https://www.health.gov.au/resources/publications/final-report-on-the-national-indigenous-bowel-screening-pilot?language=en