Colon cancer Flashcards
superior hemorhoidal / rectal arteries arise from which artery?
IMA
lower rectal cancer will have more systemic or localized spread?
systemic
in which layer of the GI tube are the lymphatics located?
submucosal
what are protective factors limiting colon cancer?
hormone replacement
NSAID use
fiber, fruits, vegetables
what type of gene is APC?
tumor suppressor
what type of gene is K-RAS?
proto oncogene
what type of gene is DCC?
tumor suppressor
what type of gene is p53?
tumor suppressor
what is the sequence of gene mutations leading to carcinoma?
APC - K-RAS - DCC - p53
what is the mutation in FAP? which chromosome?
APC gene
chromosome 5q
what is the inheritance of FAP?
autosomal dominant
what is the lifetime cancer risk by age 50 for FAP?
100%
what is the treatment for FAP?
total colectomy and rectum
what is the pathogenesis of lynch syndrome?
mismatch repair gene defects
how does lynch syndrome differ from FAP?
progression to cancer is quick with lynch
which gene is responsible for development of early adenoma?
APC
which gene is responsible for development of intermediate adenoma?
K-RAS
which gene is responsible for development of late adenoma?
DCC
which gene is responsible for development of colon carcinoma?
p53
advanced polyps may produce what screening sign?
positive fecal occult blood test
what are the screening modalities for colon cancer? what is the gold standard?
colonoscopy flexible sigmoidoscopy high sensitivity guaiac / FOBT double contrast barium enema CT colonoscopy
GOLD STANDARD: colonoscopy
colonoscopy scope can reach how far?
cecum and terminal ileum
sigmoidoscopy scope can reach how far?
splenic flexure
what does a stool guaiac blood test assay for?
peroxidase activity
what does a fecal immunochemical test assay for?
antibody
a positive stool-based test requires what next step?
colonoscopy
a positive double contrast barium enema requires what next step?
colonoscopy
what are the screening regimens for colon cancer?
colonoscopy every 10y, or
flexible sigmoidoscopy every 5y plus high sensitivity FOBT every 3 years, or
high sensitivity FOBT every year
if a patient has family hx of colon cancer when does colonoscopy start? when are they repeated?
age 40
repeat every 5 years
when do patients with IBD get screened for colon cancer? what else is done? how often is the screening?
colonoscopy every 8-10 years after symptoms
collect 4x random biopsies every 10cm
repeat every 1-2 years
when do patients with lynch syndrome get screened for colon cancer? when is it repeated?
colonoscopy age 20-25
repeat 1-2 years
when do patients with FAP get screened for colon cancer? when is it repeated?
colonoscopy age 10-12
repeat 1-2 years
what is the serum tumor marker for colon cancer?
CEA
what test should be used for equivocal CT findings?
PET
what staging is Tis?
intraepithelial
what staging is T1?
muscularis mucosa into submucosa
what staging is T2?
invades muscularis propria
what staging is T3?
invades pericolorectal tissues
what staging is T4a?
penetrates peritoneum
what staging is T4b?
invades adjacent organs
intraepithelial staging
Tis
muscularis mucosa into submucosa
T1
invades muscularis propria
T2
invades pericolorectal tissues
T3
penetrates peritoneum
T4a
invades adjacent organs
T4b
nodal staging N0
no regional node met
nodal staging N1
met in 1-3 regional nodes
nodal staging N2
met in 4 or more regional nodes
how many nodes should be examined for adequate staging?
15
where are nodes collected from?
visceral mesentery
what are the met stagings?
M0 - no met
M1 - distant met
how far must resection margins be?
5cm
resection is largely determined by what factor?
blood supply
what is involved in a low anterior resection?
rectosigmoid resection extending below the peritoneal reflection with associated mesorectum
what is involved in an abdominal perineal resection?
rectosigmoid resection including anal sphincters, anal opening, and associated mesorectum
what is involved in a colectomy?
resected colon with associated mesentery
T1, T2, T3 colorectal cancer are treated with what modality?
surgical resection
surgical resection is indicated for what staging?
T1, T2, T3
some T3, T4 colorectal cancer is treated with what modality?
surgical resection with chemo
surgical resection with chemo is indicated for what staging?
T4, some T3
N1, N2
surgical resection with chemo
N1, N2 colorectal cancer are treated with what modality?
surgical resection with chemo
liver or lung met is treated with what modality?
surgical resection with chemo
how is metastatic disease treated for colorectal cancer?
chemo
what is the treatment for Tis, T1 rectal cancer?
transanal excision
what is the treatment for T2 rectal cancer?
surgical resection
what is the treatment for T3, T4, N plus rectal cancer?
neoadjuvant chemo and resection
when is rectal cancer neoadjuvant therapy indicated?
T3 and T4
node-positivity
locally unresectable
