Red Book

Early detection of cancers

Colorectal cancer

Please note that Section 9.2 was updated in August 2018

Average risk

Age range chart

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 70-79 >80
                               

High risk

Age range chart

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 70-79 >80
        10 years prior to age of onset of affected family member


Biennial faecal occult blood test (FOBT) can reduce colorectal cancer (CRC) mortality by 16%.17 The original trials of FOBT screening used the guaiac-based FOBT, but this has been superseded by the more sensitive and specific faecal immunochemical test (ie iFOBT). Organised screening by iFOBT is recommended for the asymptomatic (average risk) population from 50 years of age every two years (A) until 74 years of age with repeated negative findings.18,19

In November 2017, the National Health and Medical Research Council (NHMRC) endorsed a new national guideline on CRC prevention and screening. Screening recommendations, which used to be determined solely on lifetime risk of CRC, now also account for absolute risk of cancer in the short term.109 Risk assessment should include determining the number and type of relatives affected by CRC, and age at diagnosis (refer to Table 9.2.1. Colorectal cancer: Identifying risk). The new guideline also changed the recommendations on CRC screening modality in people at moderate risk of CRC. Of note, iFOBT is now recommended for people in this group from 40 to 49 years of age and colonoscopy five-yearly from 50 to 74 years of age. Digital rectal examination (DRE) is not recommended as a screening tool (D), but is important in evaluating patients who present with symptoms (eg rectal bleeding).

Colonoscopy is not recommended as a screening test for people at average risk of CRC. No randomised controlled trial (RCT) has evaluated the effect of colonoscopy on CRC mortality, although trials are in progress in Spain, Sweden and the US. Colonoscopy has indirect and direct harms, including, rarely, death from the procedure (one in 10,000–14,000 colonoscopies).20, 21 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 infection, colonic perforations, bleeding). There is insufficient evidence about the use of computed tomography (CT) colonography (also refer to Chapter 15. Screening tests of unproven benefit), faecal deoxyribonucleic acid (DNA) or plasma circulating DNA tests to recommend them as alternatives to iFOBT for CRC screening.22

The 2017 NHMRC-endorsed guideline also examined an updated systematic review of trial evidence on the effects of low-dose aspirin on CRC incidence and mortality. The guideline development group considered evidence relating to the additional benefits from reduction in cardiovascular disease risk and potential adverse effects (ie haemorrhagic stroke, gastrointestinal bleeding, peptic ulcer).109 Overall, it was found that the benefits of taking low-dose aspirin outweighed the harms, and the guideline recommends that aspirin should be actively considered in all people aged 50–74 years.

Table 9.2.1

Table 9.2.1

Colorectal cancer: Identifying risk


Patients who have adenomatous polyps removed at colonoscopy are then classified as having above-average risk for the development of metachronous adenomatous polyps and CRC. Table 9.2.2 provides advice about colonoscopic surveillance and recommended frequency based on the number and histology of polyps. It is important to try to obtain information about the histology, size and number of polyps removed, as this determines the future risk of adenomas and CRC and, therefore, frequency of recommended surveillance colonoscopy.30
Table 9.2.2

Table 9.2.2

Follow-up after polypectomy

Table 9.2.3

Table 9.2.3

Test to detect colorectal cancer


Strategy

Measures to increase screening in these groups include organised approaches such as employing recall and reminder systems;32,33 recommendations by the GP for the screening;33,34 addressing capacity issues, including convenience;33,35 and minimising barriers such as cost.33,35,36 Refer to the RACGP’s Putting prevention into practice: Guidelines for the implementation of prevention in the general practice setting (Green Book).

The National Bowel Cancer Screening Program, using iFOBT, is being expanded, and by 2020 will offer biennial screening for people aged 50–74 years. GPs are critical, not just in maximising participation but in managing participants with a positive iFOBT.34,37

Participation is under-represented by Aboriginal and Torres Strait Islander peoples and culturally and linguistically diverse (CALD) peoples.38

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