colon cancer Flashcards
what is the most common type of colonic polyp and where is it commonly seen ?
hyperplastic polyp - benign
common n the rectosigmoid colon
what is the pattern associated with hyperplastic polyps ?
saw toothed or serrated pattern
what are the sub classification of adenomatous polyps ?
by shape - pedunclated and sessile
by histology - tubular and villous
what is the most common subtype of adenomatous polyps ?
tubular
which of the adenomatous polyp is associated with a higher risk of developing into colon cancer ?
villous
what are the symptoms associated with villous adenoma ?
lead to excess mucous secretions
rarley cause secretory diarrhea
watery disrrhea - hypokalemia
when does the secretory diarrhea happen in association with villous adenoma ?
when it is present in the rectosigmoid junction
what are the high risk features of a polyp ?
villous histology
what are the juvenile polyps ?
these happen in children (hamartomas)
usually in the rectum and usually pedunculated
what is the presentation of juvenile polyps ?
painless rectal bleeding
often auto amputate
what is juvenile polypsosis syndrome ?
multiple polyps (more than 10)
have an increased risk of cancer
what is petz jegher syndrome ?
autosomal dominant disorder
multiple hamartomas through out the GI tract
pigmented spots on the lips and buccal mucosa
what are the genetic pathways associated with colon cancer ?
chromosomal instability pathway
microsatellite instability pathway
why is aspirin used to prevent colon cancer ?
due to an increase in cyclooxygenase activity
what gene is found to be mutaed i colon cancer ?
DCC gene mutation
chromosome 18q
what is the chromosomal instability pathway?
adenocarcinoma pathway
somatic mutations that occur with aging
mismatch repair leads to microsatelliteinstability
what type of tumors are associated with chromosomal instability pathway ?
left sided tumors
what are the stps associated with the chromosomal instability pathway ?
step 1 : APC mutation , leads to an increase in beta catenin which activates oncogenes
step 2: KRAS mutation 3ashan y3mel polyp
step 3: p53 mutation giives rise to colo cancer
what is FAP ?
familial adenomatous polyposis autosomal dominant
germline mutation of APC
always gives rise to colon cancer
what are the FAP variants ?
gardners syndrome
turcots syndrome
what is gardner syndrome ?
polyposis
osteoma bumps on the bones
desmoid tumors
skin cysts
hypertrophy of the retinal pigment (CHRPE)
what if you find congenital hypertrophy of the retinal pigment epithelium with polyposis ?
most likely gardners syndrome
what is turcots syndrome ?
polyposis plus brain tumor
medulloblastoma or glioma
what is the mechanism of micro satellite instability ?
can rise without polyps
more in right sided tumors
what colon cancers arise from micro-satellite instability ?
HNPCC or lynch syndrome
what other cancers are associated with HNPCC ?
endometrial cancer
what is the classic case associated with HNPCC ?
patient with a right sided colon cancer that also has multiple 1st family members with cancer
what is the presentation associated with right sided colon cancers ?
exophytic
iron defeciency anemia
weight loss
microsatellite instability
what is the presentation associated with left sided colon cancer ?
LLQ pain
blood streaked stool
circumferential lesions
change in stool caliber
adenoma-carcinoma sequence
what is the most common site of metastasis of colon cancer ?
liver
what bacteria is associated with colon cancer ?
strep bovis - galaloyticus
what is the next appropriate step after identifying strep bovis endocarditis ?
colonoscopy
what tumor marker is elevated in colon cancer ?
CEA
what type of fistula is associated with colon cancer ?
colovesicular
what type of endocarditis is associated with colon cancer ?
strp bovis , gallolyticus
what gene is mutated when there is a polyp without any site of invasion ?
KRAS
what gene is mutated when there is metastasized colon cancer ?
p53
what is the order in which the gene mutation of colon cancer happens ?
KRAS
PTEn
DCC
P53
