Week 5.1 - Colorectal Cancer Flashcards
What are the majority of colorectal cancers?
adenocarcinomas - 95%
Where do you often find CRC?
2/3rds colon and 1/3rd rectum
What is the aetiology of colorectal cancer?
- 85% sporadic
- 10% familial
- 5% inheritable
- 1% IBD predisposed
what are risk factors for CRC?
- age
- males
- previous adenocarcinoma or CRC
- environment - diet, smoking, alcohol, diabetes
How do the majority of CRC’s arise?
pre-existing polyps
what is a polyp? what describes higher risk lesion?
protruding growths in colon.
no of growths, size, degree of dysplasia and villous architecture
What is an adenoma?
typically benign/pre-malignant and epithelial in origin.
How does normal epithelium become adenocarcinoma?
- activation of oncogenes,
- loss of tumour suppression genes
- loss or defective dna repair pathway genes
What are 6 signs and presentations of CRC?
- palpable mass
- altered bowel movement
- acute colonic obstruction
- rectal bleeding
- iron deficiency anaemia
- systemic weight loss/anorexia
How do we stage CRC?
- CT, PET CT and MRI for rectal tumours
TNM and dukes criteria - A high chance of cure and D poor survival - 3YSR
How do you investigate CRC?
- Colonoscopy
- CT colonography
- TNM to stage
What is beneficial about a colonoscopy?
therapeutic and diagnostic. polyps can be removed.
What are treatment options for CRC?
- 80% surgical resection - early is endoscopic
- partial hepatectomy for those metastasised improves survival
What are palliative options for CRC?
- stenting for chronic obstruction
What is FAP?
- Familial associated polyps
- multiple adenomas throughout colon - 50% affected by age 15. screening starts at 10/12 and prophylactic colectomy done at 16-25
- also find adenomas in duodenum of most
What is HNPCC?
Mutation in dna mismatch repair genes MLH1 and MSH2. leads to early onset CRC - 40+
What is MAP?
- MUTYH associated polyps - hereditary
- causes mostly right sided colonic CRC - MUTYH base excision repair gene variant. annual surveillance
Which high risk groups are screened for CRC?
- family history of adenocarcinoma - depending on how many 1st degree relatives affected
- previous adenomas and CRC screening depends on likeliness and severity
What is a FIT test?
- can be done for asymptomatic patients in screening or symptomatic patients to diagnose.
- detects faecal haemoglobin and faecal calprotectin to see if there is bowel pathology
How do you prepare for a colonoscopy?
sedation and analgesia given to prevent discomfort. strong laxatives to clear bowel
