Colorectal Cancer Flashcards
What are the risk factors for colorectal cancer? (8)
Age
Male
Previous adenoma
Environmental factors: Diet Obesity Lack of exercise Diabetes mellitus Smoking
What are the two main histological subtypes of colorectal polyps?
Tubular
Vilous
(Indeterminate tubulovilous)
What are the three main steps in the adenoma-carcinoma development?
Activation of oncogene (kras, c-myc)
Loss of tumour suppression gene (APC, p53, DCC)
Defective DNA repair pathway genes
What are the main presentations of colorectal cancer? (6)
Rectal bleeding
Altered bowel opening (diarrhoea)
Iron deficiency anaemia
Palpable rectal or right lower abdominal mass
Acute colonic obstruction if stenosing tumor
Systemic symptoms e.g. anorexia, weight loss
What is the mainstay investigation of colorectal cancer?
Colonoscopy
What are the potential risks of colonoscopy? (3)
Bowel perforation, bleeding
Risks of sedation
Bowel preparation (risk for patients with renal problems)
What radiological techniques may be used in colorectal cancer other than colonoscopy? (3)
Barium enema
CT colonoscopy
CT abdomen/pelvis
What are the disadvantages of using CT colonography? (4)
No histology
No therapeutic intervention
Ionising radiation
Risks of bowel preparation
What investigations can be used to stage colorectal cancers?
CT scan for chest/abdomen/pelvis
MRI for rectal tumours
PET scan/rectal endoscopic ultrasound in some cases
What are the classifications of Duke’s criteria?
A: tumour confined to mucosa
B: tumour extended to muscle layer
C: involvement of lymph nodes
D: distant metastatic spread
What is the main therapy in colorectal cancer?
Surgery in 80% of patients
What may be a consequence of surgery for CRC?
Stoma formation
Which types of colorectal cancer may receive chemotherapy? (3)
Duke C
Duke B if advanced
Palliative cases
What are the main forms of prevention for colorectal cancer? (2)
Adjusting lifestyle factors
Screening
What does FOBT stand for?
Faecal occult blood test
What are some of the modalities of screening for colorectal cancer?
FOBT
What age are patients in Scotland called for FOBT?
Between 50-74 years old
How often are patients in Scotland called for FOBT?
Every 2 years
What is the next stage if FOBT is positive?
Colonoscopy
What 2 main heritable conditions increase the risk of colorectal cancer?
FAP (familial adenomatous polyposis)
HNPCC (hereditary non-polyposis colorectal cancer)
How early does screening start in FAP?
Between 10-12 years old
What age are patients called for screening in HNPCC?
From 25 years old normally
What are the high risk groups for CRC? (6)
HNPCC FAP Family history of CRC IBD Previous CRC Previous adenomas
What dietary factors may increase risk of CRC? (5)
Increased red meat Increased alcohol Low fibre Low calicium Low fruit and veg intake
What are the two main morphological types of colorectal polyps?
Pedunculated
Sessile
When do you investigate for CRC in cases of iron deficiency anaemia?
Men of any age
Non-menstruating women
What surgery is normally involved in Duke’s A and cancerous polyps?
Endoscopic or local resection
When will radiotherapy be used in CRC?
Only in rectal cancer
What are the modalities of CRC screening? (5)
FOBT Faecal immunochemical test Flexible sigmoidoscopy Colonoscopy CT colonography
