How to Treat – Bowel cancer part 1: Diagnosis
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Patients under 50 Discussion of screening still needs to occur with all adult patients over the age of about 20. It is important to remember that patients classified as risk category two or three have, by definition, a significant family history of usually younger relatives who have been affected by colorectal cancer.
If discussion regarding screening options were to be delayed in all patients until the age of 50, these high-risk patients would simply not be identified until well after the age at which they should have started screening. In addition, while the NBCSP only offers free FOBT to patients over 50 of average risk, up to 10 % of all new diagnoses of bowel cancer in Australia will occur in patients under the age of 50. There is also evidence to suggest that this percentage is increasing.
It is perfectly reasonable for patients under 50, even with a negative family history, to consider starting self-funded FOBT if they are aware of the risks, benefits and potential costs of undertaking this. Now there are a large number of third-party providers( see online resources) who provide FOBT kits at a relatively modest cost.
Remember that a strategy for bowel cancer screening, guided by the NHMRC guidelines, should occur in all of your adult patients.
Staged rollout of the National Bowel Cancer Screening Program
Australian doctors face a challenge between 2016 and 2020 in accommodating the currently incomplete rollout of the NBCSP. If patients currently enrolled in the NBCSP return a negative test, then the next kit will not be sent for up to five years.
This current structure is not yet fully consistent with the national guidelines. It is therefore important to discuss with patients who have returned a negative test under the NBCSP the option of self-funding one-to-two-yearly tests in the interim to ensure their screening requirements are optimised.
Other advice for patients about bowel cancer screening Educate all adult patients on the dietary and lifestyle guidelines for reducing the risk of bowel cancer( see table 2). In addition, educate patients about the importance of a change in family history. Patients should alert their GP to a change in status if a family member is affected, and an annually updated systems review of all patients should include questions regarding a family history of colorectal cancer.
Lastly, GPs should educate patients about vigilance for interval symptoms between screening investigations, which include rectal bleeding, change in bowel habits, unexplained abdominal pain or weight loss.
Management of patients who have had adenomatous polyps The diagnosis of a polyp in a patient may significantly alter the advice that will be given regarding future screening strategies. It is
Sigmoidoscope.
important to stratify advice on the basis of the histopathology of the polyp, the discussion in consultation with the endoscopist and to do
Table 2. General guidelines to reduce the risk of colorectal cancer
Category
Recommendation
Diet The risk of CRC can be reduced if patients do the following:
• Restrict energy intake( fewer than 2500kcal a day for men; fewer than 2000kcal a day for women)
• Reduce dietary fat( less than 25 % of total energy as fat)
• Eat five or more portions of fruit and vegetables a day all year round
• Consume poorly soluble cereal fibres( eg, wheat bran), especially if at high risk of CRC
• Ensure a dietary calcium intake of 1000-200mg a day
• Reduce consumption of red and processed meats
Healthy lifestyle
The following healthy lifestyle recommendations may be protective against CRC and should be followed by all people:
• Participate in regular physical activity
• Restrict alcohol intake
• Do not smoke
Chemoprevention
Agents such as selenium supplements, aspirin, NSAIDs and selective COX-2 inhibitors may be important in the prevention of CRC, but are not recommended until further research is conducted
Type of polyps
Patients with only polyps, which are small, pale, distal and hyperplastic
High-risk adenomas: three or more adenomas Equal to or greater than 10mm or with tubulovillous or villous histology or high-grade dysplasia
Follow-up of patients with sessile adenomas and laterally spreading adenomas
Follow-up after resection of serrated adenomas and sessile serrated adenomas
Follow-up for patients with multiple adenomas
Follow-up based on two or more examinations
Table 3. Guidelines for follow-up investigation after removal of polyps Colonoscopic follow-up None
Colonoscopy at three-yearly intervals
If large and sessile adenomas are removed piecemeal, follow-up colonoscopy should be at 3-6 months to ensure complete removal If removal is complete, subsequent surveillance should then be based on histological findings, size and number of other adenomas
Currently, insufficient evidence to differentiate follow-up protocols for sessile serrated adenomas from standard adenoma follow-up guidelines Follow-up should be determined as for adenomatous polyps, taking into account parameters, such as polyp size, number and presence of high-grade dysplasia
As multiplicity of adenomas is a strong determinant of risk of metachronous advanced and non-advanced neoplasia, follow-up should be at 12 months for those with five or more adenomas and, because of the likelihood of missed synchronous polyps being present, sooner in those with 10 or more adenomas If a polyposis syndrome accounts for the findings, follow-up colonoscopy should be within one year for patients with five or more adenomas at one examination
If advanced adenomas are found during subsequent surveillance, maintaining a three-yearly schedule is prudent, but the choice should be individualised The interval can be lengthened if advanced adenomas are not found
Source: Cancer Council Australia. Clinical Practice Guidelines for Surveillance Colonoscopy, 2011.
so in compliance with the national guidelines. The guidelines for follow-up investigations after removal of polyps are outlined in table 3.
Not all polyps are of equal significance. A tiny hyperplastic polyp in the rectum is almost certainly of no significance and does not require alteration of screening guidelines from those prior to the colonoscopy.
While a small adenomatous polyp should be managed in compliance with the guidelines, there are very high-risk polyps that may require tailored advice in relation to subsequent followup. For example, if a large sessile polyp with high-grade dysplasia is removed, it may be clinically appropriate to repeat colonoscopy earlier than the suggested guidelines— sometimes in a shortened interval of 6-12 months. This is to ensure the high-risk polyp has been completely removed and has not reoccurred. As always, while recommendations from national guidelines are important, advice needs to be tailored to the individual needs of the patient.
Polyps can generally be removed colonoscopically. Traditional techniques of polypectomy, including use of hot biopsy forceps and electrocautery snare, have now been augmented by more advanced techniques, such as endoscopic mucosal resection.
With newer techniques of colonoscopic polypectomy, most polyps can be removed without resorting to abdominal surgery. However, in a small number of patients, complete colonoscopic removal is not possible and some high-grade dysplastic polyps with involved margins may mandate segmental colorectal resection.
Further investigations While most colorectal cancers in Australia are diagnosed at colonoscopy, there may be circumstances in which other investigations may be indicated.
CT colonography CT colonography is not recognised in Australia as a communityscreening tool for colorectal cancer for the following reasons: first, it has not been shown to be more accurate than conventional colonoscopy; second, it has no direct therapeutic value or the capacity to biopsy; third, it still requires bowel preparation; and finally, it carries a small risk of perforation and complications.
It may, however, be of value in patients in whom complete colonoscopy with caecal intubation cannot be accomplished. This may occur in 2-10 % of patients undergoing colonoscopy, depending on their circumstances.
Barium enema Despite now being regarded as an‘ old’ investigation, barium enema still has value in a small number of patients, particularly if colonoscopy is not readily available or CT colonography is deemed inappropriate.
It will occasionally add additional information regarding the obstructive nature of strictures or lesions.
Other investigations Occasionally, colorectal cancer will be incidentally diagnosed on investigations performed for other reasons— such as CT abdomen and pelvis, PET or ultrasonography— but these are not first-line diagnostic investigations.
20 | Australian Doctor | 2 June 2017