CM - Colorectal Cancer Flashcards
What is the pathophysiology of the adenoma-carcinoma sequence for colorectal cancer?
mutation of tumor suppressor and proto-oncogenes –> hyperproliferative cells –> more mutations
How does a high intake of dietary fat favor carcinogenesis?
increases the hepatic secretion of cholesterol and bile acids into intestine
anything increasing transit time could increase contact w possible carcinogens
What are the six most common risk factors for the dev of colorectal cancer?
Age dietary factors family hx of CRC or adenomas previous colorectal neoplasia genetic syndromes IBD
What size indicates a medium malignant potential and a high malignant potential of an adenoma?
1-2 cm
>2 cm
What histology of an adenoma indicates malignant potential?
villous > tubulo-villous > tubular
What are the clinical features of adenomatous polyps?
most commonly no symptoms
sometimes occult bleeding, but uncommon
rarely large polyps can cause obstruction
rarely villous in distal can cause secretory diarrhea
What are the clinical features of colon cancer?
right vs. left side
left can have hematochezia
uncommonly bowel perf and peritonitis
What are the four diagnostic tests for diagnosis of CRC?
FOBT = fecal occult blood test
barium enema - false+ common, cheap, lesion found requires colonoscopy
sigmoidoscopy
colonoscopy - more prep
last two can biopsy or remove during procedure
What is the treatment for hyperplastic polyps?
remove colonoscopically - can’t tell diff b/w adenomas
no regular surveillance if proves to be this
What are the treatment modalities for adenomatous polyps?
removed colonoscopically
What are the treatment modalities for carcinoma-in-situ?
if cells penetrate BM into LP but remain above muscularis mucosa = inramucosal carcinoma
endoscopic removal = curative, no lymphatics yet
What are indications for surgical resection in pts w endoscopically removed malignant polyps?
carcinoma poorly differentiated
invades veins or lymphatics
cancer w/i 2 mm of polypectomy margin
invades submucosa of BOWEL wall (not stalk)
Who is the “average risk” pt for CRC?
> 50
no “high” risk factors
asymptomatic
What is the difference b/w screening and surveillance for CRC?
screening - test for large pop of avg risk to see who is at risk
surveillance - test w high diagnostic accuracy on ppl at high risk
What are the surveillance recommendations for ppl w first degree relatives w CRC?
colonoscopies start at 40 or 10 yrs younger than youngest family member got it
every 5 yrs instead of 10, if polyps found every 3
