colorectal and anal cancer Flashcards
what is the epidemiology of colorectal cancer
- equal M:F for colonic but men have slightly more rectal cancers
- highest incidence is in europe and north america (lowest in asia, africa and south america)
what kind of diet increases the risk of colorectal cancer
diet high in fat and cholesterol (esp from animal sources), processed and red meat
risk factors for colorectal cancer (6)
- genetic syndromes/ other genetic mutations
- diet
- obesity
- alcohol (>6 units per day)
- diabetes
- smokers
what is familial adenomatous polyposis (FAP)
and autosomal dominant inherited condition characterised by hundreds of adenomatous polyps
what is the mgx for someone with familial adenomatous polyposis
prophylactic surgery at 16-25 yro -> if don’t opperate then will almost definately get colorectal cancer
extracolonic manifestations of familial adenomatous polyposis (5)
- desmoid tumours
- duodenal adenomas
- skin lesions/epidermal cysts
- osetomas in mandible and maxilla
- congenital hypertrophy retinal pigment epithelium (can be easily tested in children)
what is lynch syndrome
and autosomal dominant DNA mismatch condition where a person is predisposed to getting cancer (lifetime risk 85%)
what screening is given to those w lynch syndrome
colonoscopy every 2 years
genetic mutations associated w increased risk of colorectal cancer (not syndromes)
ACP; CTNNB1; AXIN1; hMLH1/2
possible aetiological factors for colorectal cancer (6)
- adenoma-carcinoma sequence
- IBD
- ureterosigmoidostomy (no longer performed but seen in elderly)
- acromegaly (related to serum GH/IGF1 levels)
- gastric surgery (changes in bile acid)
- irradiation
what is the distribution of tumours within the colon
majority occur on the left side
1. rectum -27%
2. sigmoid colon - 20%
3. caecum (R side, near ileum) - 14%
4. anus - 2%
what bowel screening tests may pick up a colorectal cancer (3)
- faecal occult blood and colonoscopy
- faecal immunochemical test
- flexible sigmoidoscopy
colorectal cancer presentation
- change in bowel habit
- rectal bleeding
- anaemia
- abdominal pain
- mucus/tenesmus
- abdominal mass
- weight loss
- emergency presentation (obstruction, peritonitis, bleeding etc.)
when is colonic stenting used (3)
- metastatic disease
- large bowel obstruction -> get pt fit for elective surgery
- benign strictures
6 complications of colorectal cancer resection
- anastomotic leak (high rates of this, L hemicolectomy more than R)
- wound infection
- DVT/PE
- bleeding
- nerve injury (bladder + sexual function)
- stoma complications
when to consider that there is an anastomotic leak post colorectal surgery (4)
- any deterioration in condition within 10 days
- elderly - often present w AF or respiratory symptoms
- defunctioning stoma
- metabolic acidosis, raised CRP and WCC
4 methods of tumour spread
- nodal
- vascular
- direct
- transcoelomic
Duke’s staging for colorectal cancer
A - inner lining of bowel
B - through the muscular layer
C - spread to at least 1 lymph node
D - metastases
pT tumour classification (coloncancer)
pT1 - submucosa invasion
pT2 - muscularis propria invasia
pT3 - subserosa/ non-peritonealised pericolic/ peri-rectal tissues
pT4 - perforates visceral peritoneum (4a) anddirectly invades other structures (4b)
what pre-op treatment can be given for rectal cancer (2)
- short course of radiotherapy and then surgery the following week
- long course chemo-radiotherapy and then delayed surgery for 8-12 weeks
what is transanal endoscopic microsurgery (TEMS)
a type of robotic surgery where rectal tumours are removed (full thickness or submucosal thickness) and defects can be closed
what is transanal total mesorectal excision (TaTME)
a specific surgical technique used in the treatment of rectal cancer in which the bowel with the tumor is entirely removed along with surrounding fat and lymph nodes
what is anal intraepithelial neoplasia
precancerous changes to the lining of the ansu
how is anal intraepithelial neoplasia treated
imiquimod