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Flashcards in GI19 Deck (19):
1

Colorectal Cancer: Epidemiology

-3rd most common cancer
-3rd most deadly in U.S.
-Pt. > 50 y/o
-25% have family history

2

Colorectal Cancer: Genetic types

-Familial Adenomatous Polyposis (FAP)
-Gardner's syndrome
-Turcot's syndrome
-Hereditary Nonpolyposis Colorectal Cancer (HNPCC/Lynch syndrome)

3

Colorectal Cancer: Additional Risks

-Irritable bowel
-Tobacco
-Large villous adenomas
-Juvenile polyposis syndrome
-Peutz-Jeghers syndrome

4

Colorectal Cancer: Locations

1-Rectosigmoid
2-Ascending
3-Descending

5

Colorectal Cancer: Presentation
- Ascending

-Exophytic mass
-Iron deficiency anemia
-Weight loss

6

Colorectal Cancer: Presentation
- Descending

-Infiltrating mass
-Partial obstruction
-Colicky pain
-Hematochezia

7

Colorectal Cancer: Screening

Patients > 50 y/o
-Colonoscopy or
-Occult blood test

8

Colorectal Cancer: Barium Enema X-ray

"Apple core" lesion

9

Colorectal Cancer: Tumor marker

CEA tumor marker:
-Good for monitoring recurrence
-NOT useful for screening

10

Familial Adenomatous Polyposis (FAP).

-Autosomal-Dominant
-APC gene mutation
-Chr 5
-2-hit hypothesis
-100% progress to CRC
-Thousands of polyps
-Pancolonic
-Always involves rectum

11

Gardner's syndrome.

-FAP + Osseous and Soft tissue tumors
-Congenttal hypertrophy of retinal pigment epithelium

12

Turcot's syndrome.

-FAP + malignant CNS tumor

"TURcot = TURban"

13

Hereditary Nonpolyposis Colorectal Cancer (HNPCC/Lynch syndrome).

-Autosomal-Dominant
-DNA mismatch repair gene
-80% progress to CRC
-Proximal colon always involved

14

APC gene mutation.

FAP

15

FAP + Osseous and Soft tissue tumors.

Gardner's syndrome

16

FAP + Malignant Brain tumor.

Turcot's syndrome

17

Mutation of DNA mismatch repair gene.

HNPCC/Lynch syndrome

18

What are the 2 molecular pathways that lead to CRC?

-Microsatellite instability pathway (15%)
-APC/ß-catenin (chromosomal instability) pathway (85%)

19

What is the order of genetic events leading to CRC?

"AK-53"

1-Loss of APC gene
2-K-RAS mutation
3-Loss of p53