The Nuts and Bolts of Bowel Cancer Screening

The rapid evolution of bowel cancer screening and colonoscopic surveillance guidelines continues to create confusion in primary health care. The National Bowel Cancer Screening Program (NBCSP) has been designed to screen for bowel cancer among Australians aged 50-74. 



From 2018 to 2020, every person aged 50 to 74 years of age, in Australia, will be offered bowel cancer screening. Screening will then be offered 2-yearly thereafter. This involves an immunochemical faecal occult blood test (iFOBT) kit. Unlike the previous guaiac-based kits, these more modern kits detect only colonic bleeding and do not require dietary modifications, which will hopefully result in greater compliance. 


Colorectal cancers that are detected at an earlier stage have a better outcome. Research has demonstrated that people who are invited to participate in the bowel cancer screening program have a lower risk of death. Similarly, the complete and accurate removal of pre-cancerous colonic polyps reduces colorectal cancer mortality.

A common question that patients ask is 'why not screen with colonoscopy?' The graphic below demonstrates the superiority of screening with iFOBT over colonoscopy. The overall mortality from screening colonoscopy exceeds that from FOBT, due to the inherent risks of colonoscopy. This is in addition to the vast and impractical resources required for a complete population screening colonoscopy program.

Based on the Australian Institute of Health and Welfare analysis of bowel cancer outcomes for the National Bowel Cancer Screening Program (2014), reproduced from Kim GY, Walker J, Bickersta e A, et al. The CRISP-Q study: Communicating the risks and benefits of colorectal cancer screening. Aust J Gen Pract 2018;47(3):139–44.


Bowel cancer screening is only appropriate for symptomless individuals. Over 90% of colorectal cancers are found in people over the age of 50 years, which is the rationale for commencing screening at that age. However, Australians from 45 years of age can be screened on request.

Australians who should proceed directly to Colonoscopic examination include those with symptoms and those at increased risk of colorectal cancer 

  • Per rectal bleeding
  • Iron deficiency anaemia
  • Altered bowel habits
  • Increased risk
  • Family history (See Table 1).
  • Personal history of adenomatous polyps or cancer 

Table 1 - Family History of Bowel Cancer

Tabel 1 for Bowel Cancer article


The participation level from the population is simply too low. In 2015-2016, the participation rate was only 41%. Awareness of the prevalence of bowel cancer in Australia and awareness of free screening available to eligible Australians is the key to improving this poor uptake. It’s a very simple test that can be completed in the privacy of your own home, at no cost to you. 
A common question asked is "what is the significance of a positive iFOBT result?" The rate of a positive result is 7%. Only 3.6% of these positive results (0.26% overall) will be found to have cancer. Therefore, the vast majority of patients with a positive result will not have cancer. However, many of these patients will have adenomatous polyps. 
The importance of detection and removal of adenomatous polyps, in the prevention of colorectal cancer, cannot be understated. People with a positive iFOBT result should be referred to endoscopists who provide a high quality service. High quality endoscopists spend time examining the mucosa carefully to achieve a high rate of adenoma detection. This metric is currently being measured as part of the GESA colonoscopy recertification program.



Mr Iain Skinner
Ms Audrey Yeo
Mr Michael Hong

DRs Portraits-1

Mr Iain Skinner, Ms Audrey Yeo and Mr Michael Hong are the three specialist Colorectal Surgeons in the broader Wyndham Colorectal Surgery service.  All three operate regularly at both St Vincent's Private Hospital Werribee and Fitzroy. All being subspecialty trained in Colorectal surgery they provide an experienced and high quality colorectal surgery and endoscopy service to the Wyndham area with special expertise in the multidisciplinary care of Colorectal Cancer.

Wyndham Colorectal Surgery

All three colorectal surgeons offer timely and high quality endoscopy and advanced polypectomy services, high-risk and symptomatic patients in the Wyndham area. To make an appointment call 
03 9741 9300.