large intestine tumours Flashcards
what is a colonic polyp
an abnormal growth of tissue projecting from the colonic mucosa
what is the precursor lesion in most colon cancer
adenomas
what type of inheritance is colon cancer
autosomal dominant
what is an adenoma
benign, dysplastic tumour of columnar cells or glandular tissue
what do polyps in the rectum and sigmoid present with
rectal bleeding
diagnosing polyps
- barium enema
- CT colonography
- colonoscopy
what do large villous adenomas present with
profuse diarrhoea with mucus and hypokalaemia
what happens when polyps are found
remove them with endoscopically
what are sessile adenomas characterised by
saw-tooth appearance of the crypt epithelium
what do right sided colorectal cancers originate from
sessile serrated adenomas
what kind of inheritance is FAP
autosomal dominant
what mutations causes FAP
APC gene
how many polyps is there in FAP
hundreds to thousands of colorectal and duodenal adenomas
treatment of FAP
- colectomy
- olirectal anastomosis
which side of the colon do FAP polyps reside
right side
another name for Lynch syndrome
HNPCC
what mutation causes HNPCC
DNA mismatch repair genes
MLH1
what are DNA mismatch repair genes responsible for
maintaining the stability of DNA during replication
what is the inheritance for HNPCC
autosomal dominant
where are the polyps in HNPCC
right side
where else can HNPCC occur
- stomach
- small intestine
- bladder
- skin
- brain
what are female patents at risk for in HNPCC
endometrial and ovarian cancer
how is diagnosis of HNPCC made
from family history of colon cancer at a young age
what is Turcot syndrome
FAP or lynch with brain tumour
what is Gardner syndrome
FAP + desmoid tumours, osteomas of the skull and other lesions
risk factors of colorectal cancer
- increased age
- red meats
- polyps
- family history
- IBD
- smoking
- obesity
- acromegaly
what decreases risk of colorectal cancer
- garlic
- milk
- exercise
- aspirin
pathology of colorectal carcinoma
- polypoid mass with ulceration
- spreads by direct infiltration through the bowel wall
what type of caner is colorectal cancer
adenocarcinoma
what type of prognosis does signet ring cells have
poor
symptoms of colorectal carcinoma
- change in bowel habit
- looser and more frequent stools
- rectal bleeding
- tenesmus
- anaemia symptoms
investigations for colorectal carcinoma
- colonoscopy
- double contrast barium enema
- MRI
- CT
- PET
- FOB
what is the gold standard investigation for colorectal carcinoma
colonoscopy
what does colonoscopy allow for in colorectal carcinoma
biopsy
is biopsy mandatory
yes
what is pet scanning useful for in colorectal carcinoma
detecting occult metastases
what is MRI useful for in colorectal carcinoma
evaluating suspicious lesions found on CT
treatment for colorectal carcinoma
surgery
what is gold standard for examination of colon and rectum
colonoscopy
where do most arise from
glandular crypts
what does the cancer usually start as
polyps
what mutation do polyps usually have
APC
symptoms
- change in bowel habit
- weight loss
- PR bleeding
- tenesmus
- iron deficiency anaemia
- bowel obstruction
what is tenesmus
feeling of full rectum even after opening bowels
what side is most commonly affected
left
how is the tumours classified
TNM staging
or
Dukes staging
what is dukes staging
A - tumour confined to mucosa
B- tumour invading bowel wall
C - lymph node metastases
D - distant metastases
what is main curative treatment
surgery
