248b GI cancers

Question 1

colorectal cancer - what genetic syndromes predispose people to CRC? what is mutated? other components?

Answer 1

FAP - AD APC gene mutation on 5q; pancolonic (+ rectum) with 1000’s of polyps at young age; all progress to CRC

Gardner - FAP + osseous and soft tissue tumors, dark retinal pugmentation

Turcot - FAP + malignant CNS tumor (turcot = turban)

HNPCC/Lynch syndrome - AD DNA mismatch repair genes; 80% progress to CRC; proximal colon always involved

Question 2

risk factors for CRC

Answer 2

IBD
tobacco
large villous adenomas
JPS
Peutz-jeghers syndrome

Question 3

pancreatic adenocarcinoma - where does it arise from? what part of pancreas? tumor marker?

Answer 3

pancreatic ducts –> disorganized glandular structure w/ cellular infiltration

more common in pancreatic head –> obstructive jaundice

CA-19-9

Question 4

pancreatic adenocarcinoma - prognosis? risk factors?

Answer 4

death within 1 year

tobacco #1 risk factor

chronic pancreatitis

DM

Age > 50

Jews and AA males

Question 5

pancreatic adenocarcinoma - presentation?

Answer 5

abdominal pain radiating to back

weight loss (due to malabsorption and anorexia)

Trousseau syndrome –> migratory thrombophlebitis (red, tender on palpation of extremities)

obstructive jaundice w/ palpable, nontender gallbladder

Question 6

CRC most common location? presentation based on location?

Answer 6

rectosigmoid > ascending > descending

ascending - exophytic mass (grows outward), iron deficiency anemia, weight loss (obstruction)

descending - infiltrating mass, partial obstruction, colicky pain, hematochezia (red blood)

Question 7

CRC molecular pathogenesis

Answer 7

2 pathways –> CRC

1) microsatellite instability pathway (15%): DNA mismatch repair mutation –> sporadic and HNPCC
2) APC/B-catenin (chromosomal instability) 85% –> sporadic cancer

Order of gene events= AK-53: APC loss (colon at risk) –> K-RAS mutation (adenoma) –> p53, DCC (carcinoma)

Question 8

how long does CRC take to develop?

Answer 8

10-15 years

Question 9

follow up marker for CRC?

Answer 9

CEA (carcinoembryonic antigen)

Question 10

tumor vs stone blocking bile duct in pancreas?

Answer 10

tumor - no pain, obstructive jaundice

stone - very painful

Question 10

tumor vs stone blocking bile duct in pancreas?

Answer 10

tumor - no pain, obstructive jaundice

stone - very painful

Question 11

what is activated that causes pancreatitis?

Answer 11

premature activation of trypsinogen

Question 11

what is activated that causes pancreatitis?

Answer 11

premature activation of trypsinogen