2 Polyp types are RISK FACTORS Colorectal cancer
Adenomatous and serrated polyps,
4 RISK FACTORS CRC
- familial cancer syndromes,
- IBD,
- tobacco use,
- diet of processed meat with low fiber.
MC locations
Rectosigmoid > ascending > descending.
Location for exophytic mass, iron deficiency
anemia, weight loss.
Ascending
Location for infiltrating mass,
Descending
Location for: iron deficiency
anemia, weight loss.
Ascending
“Right side bleeds”
Location for: obstruction, colicky pain.
Descending
“left side obstructs”
Bacteremia for CRC
Streptococcus bovis
Raises suspicion in males v females?
Iron deficiency anemia in
males (especially > 50 years old)
and
postmenopausal females
Screen patients 4 ways
Screen patients > 50 years old with
- colonoscopy A ,
- flexible sigmoidoscopy,
- fecal occult blood test, or
- fecal DNA test.
lesion appearance seen on barium enema x-ray B .
“Apple core”
tumor marker:
CEA
CEA good for what?
Good for monitoring recurrence, should not be used for screening.
3 Molecular pathogenesis of colorectal cancer
- FAP
- Lynch syndrome
- serrated polyp pathway
Chromosomal instability pathway: mutations in APC cause what kind of polyp dz.?
FAP
Microsatellite instability pathway: mutations or methylation of mismatch repair genes (eg, MLH1) cause what polyp syndrome?
Lynch syndrome
Chromosomal instability pathway 3 events to form carcinoma in CRC?
- Loss of APC gene
- KRAS mutation
- Loss of tumor suppressor gene(s) (p53, DCC)
Loss of APC gene causes
↓ intercellular adhesion ↑ proliferation
KRAS mutation causes
Unregulated intracellular signaling
Loss of tumor suppressor gene(s) (p53, DCC) causes
tumor formation
