Colorectal Cancer Flashcards
how common is colorectal cancer?
2nd most common cause of cancer death in UK
where are majority of colorectal cancers?
most on left side forming from pre-existing adenomatous polyps over 3-5 years
38% in rectum
21% in sigmoid
how can cancer spread?
direct spread
lymphatic spread (hence remove many lymph nodes in surgery)
blood borne spread
- liver
- lung
Transcoelomic spread (rare - throughout abdominal cavity)
what can cause colorectal cancer?
Genetic
- mutation in APC (adenomatous polyposis coli)
- Mutations of P58 gene
Predisposing condition:
- Long standing inflammatory bowel disease
how might colorectal cancer present?
emergency - bowel obstruction/bleeding
chronic (Years = not worried, months = worry):
- change in bowel habit
- colicky abdominal pain
- iron deficiency (unexplained = V important so investigate don’t just give tablets)
- rectal bleeding (mainly in left sided, wouldn’t see the blood if right sided)
- weight loss
- abdominal mass
how is colorectal cancer investigated?
barium enema (not as common) sigmoidoscopy/colonoscopy = gold standard (colonoscopy goes further) CT colonography
what is the apple core sign?
sign of colorectal cancer in barium enema
looks like an apple core
what are the components of a colonoscopy scope?
camera light irrigation air instrument channel
what do polyps look like?
mushrooms
what are the worrying signs for polyps?
> 2cm
how can polyps be removed?
cut
cauterised
no pain/temp receptors in bowel so wont be painful
what is done for polyp cancer?
depends on where it is
If it is only at the tip of the pedunculated polyp just remove and they are fine
Deeper down the cancer goes = worse prognosis
how do you prepare for a CT colonography?
faecal tagging - picolax and omnipaque - gastrografin carbon dioxide insufflation Buscopan IV to relax bowels
Is CEA a good screening tool for bowel cancer?
no
gives false positves and negatives
but can be used after surgery to check recurrence
what is the bowel screening tool used?
FOBT/FIT test
can detect polyps, cancer or just haemorrhoids
what are the next steps after colorectal cancer is diagnosed?
histopathology confirmation stage cancer - CT for chest/abdo/pelvis - MRI for rectal cancers MDT (multidisciplinary team) Surgery FOU (follow up)
what is the prognosis for metasteses from colorectal cancer compared to other cancers?
much better
can downsize metasteses if young and fit through intense chemo/radiotherapy and removing parts of organs
which cancer has better prognosis and QoL?
lower GI
What is the benefit of removing all of the fat around the cancerous section of the bowel/rectum?
also removes lymph nodes
Increases survival hugely
stage 1 and 2?
superficial
40%
stage 3?
entered muscularis
stage 4?
metastases
unstaged?
already died so cant tell
what does superior mesenteric supply?
all small bowel
2/3rds large bowel
