Stomach_GIST

Question 1

What is the most common mesenchymal-derived tumor fo the intestinal tract?

Answer 1

GIST

Question 2

GISTs acount for what % of all GI neoplasms?

Answer 2

1%

Question 3

What protooncogene is associated with GIST?

Answer 3

KIT (CD117)

Question 4

What does imatinib mesylate do?

Answer 4

Inhibitor of tyrosine kinases ABL, BCR-ABL, KIT and PDGFR

Question 5

Use of imatinib has increased the median survival of stage IV GIST to

Answer 5

5 years from 15 months

Question 6

Mean age of GIST presentation

Answer 6

60 years - slight male predominance

Question 7

What % of GIST patients will present with a GI bleed?

Answer 7

25% due to erosion of the overlying mucosa

Question 8

Most GISTs arise from what organ?

Answer 8

60% stomach, 25-30% small intestine, 10% frm esophagus or rectum

Question 9

What is the most frequent site of GIST mets?

Answer 9

Liver and peritoneum. LN mets are rare - except in peds

Question 10

What is different about pediatric GIST biology?

Answer 10

Peds cases have LN mets, multifocal disease, female predominance, absence of KIT or PDGFRa mutation

Question 11

The KIT protooncogene is found on what chromosome?

Answer 11

4q11 -q12

Question 12

Which exon mutation is associated with worse clinical behavior in GISTs?

Answer 12

Exon 9 worse than exon 11 due to poor imatinib responsiveness

Question 13

What are the three most important factors that independently predict recurrence of localized GIST?

Answer 13

Mitotic rate, tumor size, and tumor location

Question 14

Preoperative assessment and staging of primary GIST

Answer 14

abd/pelvis CT scan + CXR

Question 15

What care should be taken when operating on GISTs?

Answer 15

Avoid excessive tumor manipulation: can cause bleeding or rupture leading to seeding of the peritoneum

Question 16

What margins are needed for GIST?

Answer 16

1-2 cm. GISTs displace rather than infiltrate adjacent structures

Question 17

What did the ACSO Group Z9001 study show?

Answer 17

Adjuvent imatinib use for 3cm or larger GISTs demonstrated benefit in recurrence-free survival.

Question 18

What are the side effects of imatinib?

Answer 18

Diarrhea, abdominal discomfort, dermatitis, periorbital or peripheral edema

Question 19

Is there a role for neoadjuvent imatinib use for GIST?

Answer 19

Yes. Can down-size the tumor and effect nature of surgery a patient receives

Question 20

What are the NCCN guidelines for CT follow-up following GIST resection?

Answer 20

3-6 months x 5 years, then annually thereafter

Question 21

What is the medial time to recurrence for GIST?

Answer 21

18-24 months

Question 22

What is the Cameron algorithm for GIST recurrence?

Answer 22

Start imatinib. If tumor responds in 2-6 months or focal resistance to imatinib consider surgery or other debulking measures and continue imatinib. If no response to imatinib, increase dose and/or seek alternative chemotherapy.