Guidelines for preventive activities in general practice

Cancer

Colorectal cancer

      1. Colorectal cancer

Cancer | Colorectal cancer

Screening age bar (average risk)

0-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 ≥80

Australia has one of the highest incidence rates of colorectal cancer in the world. Colorectal cancer was the third most commonly diagnosed cancer in Australia in 2018; an estimated 15,713 Australians were diagnosed and 5326 died of the disease in 2022.1 

Colorectal cancer screening using the immunochemical faecal occult blood test (iFOBT) is highly cost effective. The current National Bowel Cancer Screening Program (NBCSP) sends iFOBT tests to people aged 50–74 years every 2 years. Participation in the NBSCP in 2020–21 is only 41%2 and general practice plays an important role in identifying those who are under-screened and in endorsing the NBCSP. 

The National Health and Medical Research Council (NHMRC) endorsed an update to the Clinical practice guidelines for the prevention, early detection and management of colorectal cancer in September 2023, which included a recommendation to commence iFOBT screening for the general (average risk) population from age 45 years. Currently, the NBCSP will continue to send iFOBT kits to people aged 50–74 years. 

Due to the potential harms of colonoscopy and additional costs to the health system of this procedure, colonoscopy is only recommended as a screening test for people who are at least at moderate risk of colorectal cancer.3

 
Box 1. Identifying risk3
 
Adults without symptoms
Risk level Average
Definition People with no symptoms (age 45–74 years)
According to family history
Risk level Category 1: Average or slightly increased (age 45–74 years) Category 2: Moderately increased Category 3: Individuals at potentially higher risk, where Lynch syndrome has been excluded
Definition An individual should be advised that their risk of developing colorectal cancer is:
  • near-average risk if no family history of colorectal cancer
  • above average, but less than twice the average risk, if they have only one first-degree relative with colorectal cancer diagnosed at age ≥60 years.
 
This level of risk is still not high enough to justify colorectal cancer screening by colonoscopy.
An individual should be advised that their risk of developing colorectal cancer is at least two times higher than average, but could be up to four times higher than average, if they have any of the following:
  • only one first-degree relative with colorectal cancer diagnosed before age 60 years
  • one first-degree relative and one or more second-degree relatives with colorectal cancer diagnosed at any age
  • two first-degree relatives with colorectal cancer diagnosed at any age.
 
Include both sides of the family when assessing an individual’s risk category for colorectal cancer. Criteria for category 2 and category 3 can be met by inclusion of relatives from both sides of the family.
An individual should be advised that their risk of developing colorectal cancer is at least four times higher than average, but could be up to 20 times higher than average, if they have any of the following:
  • two first-degree relatives and one second-degree relative with colorectal cancer, with at least one diagnosed before age 50 years
  • two first-degree relatives and two or more second-degree relatives with colorectal cancer diagnosed at any age
  • three or more first-degree relatives with colorectal cancer diagnosed at any age.
 
Include both sides of the family when assessing an individual’s risk category for colorectal cancer. Criteria for category 2 and category 3 can be met by inclusion of relatives from both sides of the family.
 
 
 
Relative risk   At least two times higher than average, but could be up to four times higher than average. At least four times higher than average, but could be up to 20 times higher than average.
Percentage of Australian population4 98 1-2 <1
Lifetime risk to age 75 years (assuming no colorectal cancer screening) Approximately 5–10% Approximately 15–30% Approximately 30–40%

Screening

Recommendation Grade How often References
Immunochemical faecal occult blood testing (iFOBT) every 2 years is recommended starting at age 45 years and continuing to age 74 years for those at average risk of colorectal cancer. Conditionally recommended Every 2 years 5
Colonoscopy is not generally recommended for screening people at average or slightly increased risk according to their family history. Generally not recommended N/A 6,7,8

Case finding

Recommendation Grade How often References
For people at moderately increased risk of colorectal cancer:
  • colonoscopy should be offered every 5 years starting at 10 years younger than the earliest age of diagnosis of colorectal cancer in a first-degree relative or age 50 years, whichever is earlier, to age 74 years.
Conditionally recommended Colonoscopy every 5 years 6
For people at potentially higher risk of colorectal cancer, where Lynch syndrome has been excluded:
  • colonoscopy should be offered every 5 years starting at 10 years younger than the earliest age of diagnosis of colorectal cancer in a first-degree relative or age 40 years, whichever is earlier, to age 74 years.  
Conditionally recommended Colonoscopy every 5 years 3
Refer the following individuals to a clinical genetics service or familial cancer centre.

People with a personal history of colorectal cancer and any of the following features:
  • isolated colorectal cancer diagnosed under age 50 years*
  • personal history of colorectal cancer and a second Lynch syndrome associated cancer (including two colorectal cancers)
  • personal history of colorectal cancer and a family history of one or more first-degree or second-degree relatives with colorectal or endometrial cancer, with at least one of the cancers diagnosed under age 50 years
  • personal history of colorectal cancer and a family history of two or more first-degree or second-degree relatives with a Lynch syndrome associated cancer, regardless of the age the cancers were diagnosed.
 
People with a family history with any of these features:
  • family history of two or more first-degree or second-degree relatives with colorectal or endometrial cancer, at least one of the cancers diagnosed under age 50 years
  • family history of three or more first-degree or second-degree relatives with a Lynch syndrome related cancer, regardless of the age the cancers were diagnosed.
 
*As some familial cancer services may have a lower referral age, please seek advice from your local genetics service.
Lynch syndrome–associated cancer includes adenocarcinoma of the colorectum, endometrium, small intestine, stomach, ovary, or pancreas, transitional cell carcinoma of the ureter or renal pelvis, cholangiocarcinoma, brain tumour, sebaceous gland tumours, keratoacanthoma.
Conditionally recommended N/A 3,9

Preventive activities and advice

Recommendation Grade How often References
For people at higher-than-average risk, consider in consultation with a healthcare professional (refer to Further information) low-dose (100 mg) aspirin daily from age 45 to 70 years. Practice point N/A 10
Counsel all patients that the following are associated with lower colorectal cancer risk:
  • eating a healthy diet, including plenty of vegetables, fruit and whole grains while minimising intake of red meat, barbequed/grilled meat and processed meat
  • maintaining a healthy body weight
  • undertaking regular physical activity
  • avoiding or limiting alcohol intake
  • not smoking.
Practice point N/A 11

Colonoscopy is not recommended as a screening test for people at average risk of colorectal cancer; despite this, colonoscopy is common in high socioeconomic areas.3 

Colonoscopy has indirect and direct harms including, rarely, death from the procedure (one in 10,000–14,000 colonoscopies). Harm may be caused by the bowel cleanout prior to the procedure (eg dehydration, electrolyte imbalances), sedation used during the procedure (eg cardiovascular events), or the procedure itself (eg colonic perforations, bleeding).4,12,13 

General practice can play an important role in increasing participation in the NBCSP.10,11,14,15 Identifying those who are under-screened when they consult, potentially using information accessed via the National Cancer Screening Register, is an important element of this. The implementation of the Alternative Access Model means that GPs can provide NBCSP kits to all eligible patients, including their under-screened patients, as a key strategy to increase participation in bowel cancer screening. Additional ways to increase screening participation include GP endorsement messages before the NBCSP kit arrives (by SMS or letter), addressing individual patient concerns and barriers to screening, and establishing recall and reminder systems. 

Until a decision is reached by the NBCSP in relation to the recommendation to commence iFOBT screening from age 45 years, GPs can order an iFOBT as a screening test for people aged 45–50 years through their pathology provider.

 
Aspirin use

Chemoprevention trials for calcium, some vitamin supplementation, selenium and statins, have provided mixed evidence of benefit. The strong evidence for benefit has emerged from observational studies of exposure to nonsteroidal anti-inflammatory drugs, especially aspirin.10 

Results from randomised controlled trials about the use of aspirin in the primary and secondary prevention of colorectal cancer and adenomas are now available and point to a similar benefit to that associated with screening by colonoscopy in people aged <70 years.10 Aspirin is an affordable and accessible option, and has other benefits such as cardiovascular protective effects, and relatively no significant side effects, although these side effects increase with age.10 It is important to note that the benefits for aspirin in cancer prevention become apparent after a latency period of 10 years, and it is less studied in older people, especially women.10

Participation in screening is under-represented by Aboriginal and Torres Strait Islander peoples. There are several barriers to participation in the NBCSP for Aboriginal and Torres Strait Islander people, including limited knowledge about bowel cancer and screening, privacy and storage of samples at home, cultural norms about faeces and low English literacy. The Alternative Access Model was initially piloted in Aboriginal Controlled Community Health Organisations and was shown to increase participation in the NBCSP.14,16

For further specific recommendations for Aboriginal and Torres Strait Islander people, please refer to the National guide to a preventive health assessment for Aboriginal and Torres Strait Islander people, Chapter 15: Prevention and early detection of cancer – Prevention and early detection of colorectal (bowel) cancer.

Colorectal cancer: A resource card for general practitioners, Optimal Care Pathways, I-PACED (Implementing Pathways for Cancer Early Diagnosis) resources | Cancer Council Victoria

  1. Cancer Australia. Bowel cancer: Bowel cancer (colorectal cancer) in Australia statistics. Cancer Australia, 2022 [Accessed 27 June 2023].
  2. Australian Institute of Health and Welfare. Cancer screening programs: Quarterly data. AIHW, 2023 [Accessed 27 June 2023].
  3. Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Cancer Council Australia, 2023 [Accessed 31 October 2023].
  4. Emery JD, Pirotta M, Macrae F, et al. ‘Why don’t I need a colonoscopy?’ A novel approach to communicating risks and benefits of colorectal cancer screening. Aust J Gen Pract 2018;47(6):343–49. doi: 10.31128/AJGP-11-17-4386.
  5. Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Summary of recommendations for population screening. Cancer Council Australia, 2023 [Accessed 31 October 2023].
  6. Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. 5. Summary of recommendations for risk and screening based on family history. Cancer Council Australia, 2023 [Accessed 31 October 2023].
  7. Viiala CH, Zimmerman M, Cullen DJE, Hoffman NE. Complication rates of colonoscopy in an Australian teaching hospital environment. Intern Med J 2003;33(8):355–59.
  8. Rabeneck L, Paszat LF, Hilsden RJ, et al. Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice. Gastroenterology 2008;135(6):1899–906, 906 e1.
  9. Cancer Institute NSW eviQ. Colorectal cancer or polyposis – Referring to genetics. Cancer Institute NSW eviQ, 2022 [Accessed 27 June 2023].
  10. Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. 2.1.2 Chemopreventive candidate agents. Cancer Council Australia, 2023 [Accessed 31 October 2023].
  11. World Cancer Research Fund, American Institute for Cancer Research. Continuous update project expert report 2018. Diet, nutrition, physical activity and colorectal cancer. WCRF, AICR, 2018 [Accessed 8 April 2024].
  12. Lew J-B, St John DJB, Macrae FA, et al. Evaluation of the benefits, harms and cost-effectiveness of potential alternatives to iFOBT testing for colorectal cancer screening in Australia. Int J Cancer 2018;143(2):269–82.
  13. Australian Commission on Safety and Quality in Health Care. Third Australian atlas of healthcare variation. 2.1 Colonoscopy hospitalisations, all ages. ACSQHC, 2018 [Accessed 27 June 2023].
  14. Department of Health and Aged Care. Alternative access to bowel screening kits training guide. Department of Health and Aged Care, 2024 [Accessed 27 June 2023].
  15. Trevena LJ, Meiser B, Mills L, et al. Which test is best? A cluster-randomized controlled trial of a risk calculator and recommendations on colorectal cancer screening behaviour in general practice. Public Health Genomics;4:1–16. doi: 10.1159/000526628. Epub ahead of print. PMID: 36195055.
  16. D’Onise K, Iacobini ET, Canuto KJ. Colorectal cancer screening using faecal occult blood tests for Indigenous adults: A systematic literature review of barriers, enablers and implemented strategies. Prev Med 2020;134:106018. doi: 10.1016/j.ypmed.2020.106018. PMID: 32057956.
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