Colorectal Cancer Flashcards
Which % of colorectal cancer is sporadic?
85%
What’s the difference between FAP and HNPPC?
FAP=germline mutation of a tumour suppressor gene
HNPPC=mismatch of DNA repair genes
What is FAP associated with?
> 100 adenomas in colon
High malignancy risk
How often do those with FAP need a colonscopy?
Annually from 10 onwards
Where do the majority of cancers arise from?
Pre-existing polyps
What are pedunculated adenomas?
Upright
What’re sessile adenomas?
Flat
What transcription factors are associated with activation of oncogenes?
C-myc
K-rays
What transcription factors are associated with the loss of tumour suppressor genes?
APC
P53
DCC
What’s microsatelite instability?
Defective DNA repair pathway genes
Radiography is only used for which type of cancer?
Rectal only
S+S of colorectal cancer
Rectal bleeding
Altered bowel openings to loose stools for more than 4 weeks
Iron deficiency anemia in men of any age and non-menustrating women
Palpable rectal or lower abdominal mass
Systemic symptoms of malignancy eg weight loss
Why do we use colonoscopies?
Allows tissue biopsies to be taken
Can remove polyps
What’s taken before a colonoscopy?
Laxatives
What 3 Ix are used for diagnosing colorectal cancer?
Colonoscopy
Barium enema
CT colonography
What Ix are used in the staging of colorectal cancer?
CT chest/abdo/pelvis MRI PET Duke’s staging -the closer to duke’s D, the worse
FIT vs FOBT screening
FIT (faecal immunological test)
- newer, more reliable
- can be used to disregard cancer at different GP practices
- if +ve=colonoscopy
- can alter the cut off for different groups
- more user friendly
FOBT=faecal occult blood test
- old test
- not as reliable
3 other methods of screening apart from FIT/FOBT
Flexible sigmoidoscopy
Colonoscopy
CT colongraphy
What’re the continence factors?
Anatomical
- puborectalis sling
- sphincter complex
- Anal cushions
Rectal compliance
Stool consistency
Central control
Anorectal sensation
What’s screening?
Presumptive identifications of an unrecognised disease in an apparently healthy, asymptomatic population by using tests which can be easily and quickly distributed
Presentation of colorectal cancer
Colicky abdominal pain Rectal bleeding Change in bowel habits Weight loss Tenesmus Fatigue Vomiting
What is involved in pre-op management in colorectal cancer?
Colon and rectum treated as 2 separate entities MDT discussion Anaesthetic assessment stoma nurse appointment MRI Neoadjuvant chemo May need pre op stoma formation
What’re the principles of bowel astomosis?
Tension free Well perfused Well oxygenated Clean surgical site Acceptable systemic state
Which stoma has a spout?
Illeostomy
