Australian Doctor 11th April 2025 | Page 26

26 HOW TO TREAT: COLORECTAL CANCER: DIAGNOSIS

26 HOW TO TREAT: COLORECTAL CANCER: DIAGNOSIS

11 APRIL 2025 ausdoc. com. au at higher risk for a sinister cause. Age is an important factor, with the risks of colorectal cancer highest in the over-50s. However, increasing prevalence in younger patients means there are still significant risks of colorectal cancer in patients aged in their 40s, and, distressingly, there are still risks for patients in their 20s and 30s. The presence of other symptoms, listed in box 1, are a cause for concern, and their corresponding investigations are likely to be required.
Physical examination includes abdominal examination looking for masses, as well as perineal examination and digital rectal examination to look for a perianal cause of the bleeding.
Then, calculate the patient’ s risk, discuss it with them, and record this discussion in the patient’ s file for medicolegal reasons. This needs to be balanced against the risk of colonoscopy( see box 2).
Older patients with sinister type symptoms such as dark red bleeding or changes in bowel habit will almost certainly need consideration of colonoscopy. A young woman in her 20s with isolated bright red bleeding and perianal pain is unlikely to need colonoscopy. However, if after initial treatment the symptoms remain, consider referral for both investigation and management.
Box 1. Symptoms of large bowel cancer or other significant large bowel pathology
• Persistent and unusual change in bowel habit lasting more than two weeks.
• Blood in the faeces.
• Persistent or unusual abdominal pain.
• Weight loss and anorexia.
• Symptoms of anaemia.
Box 2. Risks of colonoscopy
• Risk of perforation of the large bowel, approximately 1 in 2000-3000.
• If perforation does occur, there is a significant likelihood of the patient needing abdominal surgery and a possible( likely temporary) stoma formation.
• Risk of bleeding after removal of polyps or biopsies, about 1 % depending on the size of the polyp.
• General risks of anaesthesia.
• Risks of bowel preparation( dehydration, renal impairment, falls risk, especially in the elderly).
Table 1. Guidelines for stratification of risk of CRC in the Australian population
Category
Category 1 Those at or slightly above average risk( this covers about 98 % of the population); up to two times the relative risk
Category 2 Those at moderately increased risk( covers 1 – 2 % of the population); 3-6 times the relative risk
Category 3 Those at potentially high risk( covers less than 1 % of the population); at least seven times the relative risk
Detail
• No personal history of CRC or ulcerative colitis and no confirmed family history of CRC, or
• One first-degree( parent, sibling, child) or second-degree( aunt, uncle, niece, nephew, grandparent, grandchild) relative with CRC diagnosed at age 55 or over
Screening guidelines:
• FOBT at least every two years from the age of 45
• It is important to advise individuals to see their doctor if they develop symptoms of CRC for consideration of colonoscopy
• One first-degree relative with CRC diagnosed before the age of 55, or
• Two first-degree relatives with CRC diagnosed at any age
• One first-degree relative and at least two second-degree relatives diagnosed with colorectal cancer at any age
Screening guidelines:
• Offer colonoscopy every five years starting at 45, or at an age 10 years younger than the age of youngest CRC diagnosis in the family, whichever comes first
• CT colonography is acceptable as an alternative if there is a contraindication to colonoscopy
• Consider FOBT in intervening years; colonoscopic follow-up is necessary for those with a positive FOBT
• Three first-degree relatives diagnosed with CRC of any age
• Three first- or second-degree relatives diagnosed with CRC, with one relative diagnosed less than 55 years of age
Screening guidelines:
• Offer colonoscopy every five years starting at 45, or at an age 10 years younger than the age of youngest CRC diagnosis in the family, whichever comes first
• CT colonography is acceptable as an alternative if there is a contraindication to colonoscopy
• Consider referral to a family genetics clinic
The latest guidelines include information on high-risk genetic syndromes( such as Lynch syndrome and familial adenomatosis polyposis, see figure 1) with individual recommendations
Source: Cancer Council Australia 2023 6
Screening in the asymptomatic population
The 2023 NHMRC guidelines for
stratification of risk of CRC in
the Australian population appear
in table 1. The most significant
changes are that family members
include both sides of the family( the
relatives do not need to be all on the
same side); the removal of the use
of barium enemas and flexible sigmoidoscopy
for screening; and individual
recommendations for each of
the high-risk cancer syndromes.
Most Australians will be at average
risk or slightly above average risk
( Category 1). For these patients, FOBT
is the current recommendation for
ages 45-74. Under the current NBCSP,
adult patients are sent an FOBT in the
mail at age 50, and repeat testing is
performed every two years until age
74. The government has not made
a commitment yet to send screening
kits to the expanded age group of
45-49 years.
Community uptake of FOBT has remained stubbornly low at
Figure 1. Familial adenomatosis polyposis.
around 43 %, although this is an
improvement on the 35 % previously recorded. 6 There is strong evidence to suggest that support, validation and confirmation of this program by GPs will improve uptake. 6 Therefore, conversations between GPs and their patients form a vital part of the screening program and should be
45-49 being included in the screening guidelines.
Further modelling showed that lowering the screening age further to 40 would still reduce the disease burden further and be somewhat cost-effective. 6 The taskforce decided to recommend against low-
Also consider screening in patients over the age of 74. Although they are not included in the NBCSP, as for patients aged 40-44 years, it would be reasonable to continue screening for healthy adults between the ages of 75 and 85 who have had a discussion with
population screening tool. The US has typically used colonoscopy, with both the American Cancer Society and the US Preventive Services Task Force( USPSTF) recommending colonoscopy from the age of 45. 7 However, this approach has not been followed in Australia because of the
only once, allows for a colonoscopy without a stated reason.
Colonoscopy has about a 10-15 % better detection rate than FOBT in the asymptomatic patient. However, this increased diagnosis needs to be balanced against the risks of colonoscopy( see box 2). If the patient
documented appropriately.
PATIENTS UNDER 50 OR OVER 74 Although numerous changes are being considered, one of the most significant is the change in screening age to 45. This has been
Community uptake of FOBT has remained stubbornly low at around 43 %, although this is an improvement on the 35 % previously recorded.
cost burden of colonoscopy over the entire population.
Changes to the MBS have also made it difficult for patients to undergo a colonoscopy for screening purposes only. The MBS item number 32222( endoscopic examination
understands and agrees to the risks, then it is reasonable to proceed with the colonoscopy. 7
OTHER SCREENING AND PREVENTION ADVICE Educate all adult patients regarding
prompted by the large increase in
of the colon to the caecum by colo-
dietary and lifestyle guidelines to
cancers in those aged younger than
ering the screening age to 40; how-
their GP regarding the possible ben-
noscopy, for a patient) requires a
reduce the risk of bowel cancer( see
50. Modelling performed on behalf
ever, there is a recommendation
efits and potential harms.
specific indication( see box 3). How-
box 4). It is also important to advise
of the NHMRC showed both a signif-
that it is reasonable to start screen-
ever, item 32228( endoscopic exam-
patients that their family history
icant reduction in disease burden as
ing at age 40 for patients who have
THE ASYMPTOMATIC PATIENT
ination of the colon to the caecum
can change; educate them about
well as an increase in cost-effective-
had a discussion with their GP
AT AVERAGE RISK WHO DESIRES
by colonoscopy, other than a service
the importance of a family history
ness for lowering the screening age to 45. 6 This has led to patients aged
regarding the possible benefits and potential harms.
COLONOSCOPY In Australia, FOBT is used as a
to which item 32222, 32223, 32224, 32225, or 32226 applies), applicable
of bowel cancer and the need to alert their GP if a family member is