CPG: Prevention, Early Detection, and Management of Colorectal Cancer Flashcards
Describe the CPG for dietary and lifestyle strategies to reduce CRC risk
- Folic acid intake should not exceed 1mg per day in those who are non-pregnant, and no more than 200mcg should be used as a supplement (low and high dose appear to stimulate CR carcinogenesis)
- The CPG recommends the advice from the World Cancer Research fund on reduction of colorectal cancer risk, namely:
- Being physically active
- Consuming wholegrains and fibre
- Consuming dairy and calcium supplements
- Avoiding red meat and processed meat
- Avoiding alcohol and obesity
Discuss the use of Aspirin and NSAIDS for the prevention of CRC
For all people aged between 50-70 years who are at average risk of CRC; aspirin should be actively considered to prevent CRC. A low dose of 100-300mg is recommended for at least 2.5 years and the benefit for cancer prevention is only seen after 10 years.
For patients at high risk of CRC due to Lynch Syndrome carrier status, Aspirin should be commenced from the age of screening colonoscopy (usually 25). 600mg per day has been shown to be effective, but lower dosages may be just as effective and are recommended by the CPG.
In patients with FAP in whom surgery cannot be performed, an NSAID (e.g. Sulindac) is recommended by the CPG.
Aspirin’s chemopreventive effect against CRC is attributed to its ability to inhibit COX-1 in platelets, prevent the release of lipid or protein mediators of inflammation and subsequently decrease COX-2 expression in colorectal tissues
What is the recommended age-group for population screening for colorectal cancer in Australia and NZ? Why?
The Australian screening program uses IHC FOBT in patients between 50-74 every two years.
In NZ, the same test is offered to those between 60-74. This is primarily due to limited resources and therefore cost-efficiency in the NZ system.
Describe stratification of risk in patients with a family history of colorectal cancer.
How should these individuals be managed?
- Slightly increased risk (up to 2x average risk)
- One first degree relative with CRC >55 years
- Screening not justified; consider FOBT every two years from 45. - Moderately increased risk (3-6x average risk)
- One first degree relative with CRC <55
- Two first degree relatives with CRC at any age
- One first degree and at least two second-degree relatives at any age
- FOBT every two years from age 40 and 5-yearly colonoscopy from age 50 or 10-years younger than youngest cancer (whichever is earliest)
- Consider Aspirin - High risk (7-10 times average risk)
- At least three first or second degree relatives with CRC, at least one of which is <55
- At least three first degree relatives diagnosed with CRC at any age.
- Refer to genetic specialist
- FOBT every two years from age 35 and 5-yearly colonoscopy from age 45
- Consider Aspirin
Outline colonoscopic surveillance of individuals with FAP
Individuals with the APC mutation and their first degree relatives (who have declined genetic testing or in whom the mutation in not identifiable) should be offered colonoscopy from age 10 or earlier if GI symptoms are present. Annual colonoscopy should be performed until colectomy is undertaken.
In FAP Flexible sigmoidoscopy is sufficient as adenomas occur simultaneously throughout the colon
In AFAP surveillance should be with colonoscopy as the first adenomas may arise in the proximal colon, though this can be deferred to the age of 18 as polyps arise later cf FAP.
What operation should be offered to patients with FAP and AFAP?
Total colectomy and ileorectal anastomosis should be reserved for patients with rectal adenomas considered easily controllable by endoscopy and <1000 polyps. Proctocolectomy with end-ileostomy is rarely needed (Syngas et al). Annual surveillance of the rectum is required with this approach.
Some patients with AFAP can be managed with colonoscopic polypectomy at one-two yearly intervals. If surgery is required, then colectomy with ileorectal anastomosis is almost always performed because of the small numbers of polyps in the rectum.
When should MAP or MUTYH-associated Polyposis be considered?
Referral to a genetics service for germ-line testing for MAP should be considered for persons with:
- a cumulative adenoma count >20 at any age
- >10 adenomas and one of the following:
*age under 50
*synchronous colon cancer
*both adenomas and serrated polyps where adenomas dominate
*family history suggestive of recessive inheritance
Outline colonoscopic surveillance for individuals with MAP
Bi-allelic mutation carriers should have colonoscopy every two years starting at age 18-20. If polyps are detected, annual colonoscopy may be required to address the polyp burden. If the polyps are too numerous, colectomy with ileorectal anastomosis should be offered with annual surveillance of the rectum.
Outline colonoscopic surveillance for individuals with Juvenile Polyposis Syndrome
Colonoscopy in JPS individuals should commence at age 12-15 or earlier if symptoms are present. It should be repeated every 1-3 years depending on polyp burden. Colectomy is indicated if polyps cannot be managed endoscopically.
What are the CPG recommendations for imaging surveillance in colon cancer?
For patients with treated stage II/III disease, a suitable approach to imaging surveillance may involve 12-monthly CT of the chest, abdomen, and pelvis.
For patients with stage IV disease, who have undergone resection with curative intent, a suitable approach to imaging may involve CT of the chest, abdomen, and pelvis every 6 months.
What are the CPG recommendations for MRI reporting of rectal cancer cases?
- High resolution sequences must be performed
- Additional sequences in the coronal plane to the anal canal are required for low tumours
Reports must include:
- Distance from the anal verge (puborectalis sling)
- Relationship to the peritoneal reflection
- T-staging including spread in mm beyond muscularis
- N-staging and pelvic LN status using morphology
- EMVI status
- CRM status using 1mm as a cut-off distance
Describe the CPG statements regarding pathological reporting of colorectal cancer
- TNM staging should be used
- DNA mismatch repair analysis should be performed in all colorectal cancer cases
- BRAF mutations should be performed in conjunction with DNA MMR studies to differentiate between sporadic and familial cases
- RAS testing should be carried on all patients with metastatic colorectal cancer at time of diagnosis
- Synoptic reporting should be used
What are the CPG statements on effective treatment for “early rectal cancer”?
Early rectal cancer is defined as T1/2, N0, M0.
- These should be discussed at a colorectal MDT
- Radical resection is recommended for T1sm3 tumours and for those T2 tumours who are considered for fit for radical surgery
- TAMIS and TEMS have not been shown to be superior to trans-anal excision. Regardless it is essential to obtain clear resection margins.
What practice point do the CPGs have to say about radiation therapy in the context of local excision?
Application of radiotherapy before or after local excision of rectal cancer may reduce the risk of local recurrence. However, it may have an adverse effect on bowel function.
What evidence-based recommendation do the CPGs make about stenting in acutely obstructed patients who are potentially curable?
In patients with acute obstruction due to left-sided colorectal cancer who are potentially curative, the use of stenting as a bridge to surgery is not recommended as standard treatment, due to the potential risk of tumour perforation and conversion of a curative case to a palliative case.
For patients with potentially curable left-sided obstructing colonic cancer who are considered to be at increased risk of post-operative mortality, stent placement may be considered as an alternative to emergency surgery.
What is the implication of anti-VEGF treatment in the context of colonic stenting?
Retrospective series have demonstrated that perforation risk is higher in patients who are treated with Bevacizumab before or after stent installation.
What is the role for peritonectomy in the treatment of recurrent and primary colorectal cancer with peritoneal involvement according to the 2018 CPGs?
What subsequent study addresses this recommendation?
For patients with colorectal peritoneal metastases (either synchronous or metachronous to the primary), consider cytoreduction with perioperative intraperitoneal chemotherapy. Where this procedure is suitable, offer referral to a centre with the necessary expertise and infrastructure to perform this procedure.
PRODIGE-7 (Lancet 2021) concluded that “considering the absence of an overall survival benefit after adding HIPEC to cytoreductive surgery and more frequent postoperative late complications with this combination, our data suggest that cytoreductive surgery alone should be the cornerstone of therapeutic strategies with curative intent for colorectal peritoneal metastases.”
