Stomach_GIST Flashcards
What is the most common mesenchymal-derived tumor fo the intestinal tract?
GIST
GISTs acount for what % of all GI neoplasms?
1%
What protooncogene is associated with GIST?
KIT (CD117)
What does imatinib mesylate do?
Inhibitor of tyrosine kinases ABL, BCR-ABL, KIT and PDGFR
Use of imatinib has increased the median survival of stage IV GIST to
5 years from 15 months
Mean age of GIST presentation
60 years - slight male predominance
What % of GIST patients will present with a GI bleed?
25% due to erosion of the overlying mucosa
Most GISTs arise from what organ?
60% stomach, 25-30% small intestine, 10% frm esophagus or rectum
What is the most frequent site of GIST mets?
Liver and peritoneum. LN mets are rare - except in peds
What is different about pediatric GIST biology?
Peds cases have LN mets, multifocal disease, female predominance, absence of KIT or PDGFRa mutation
The KIT protooncogene is found on what chromosome?
4q11 -q12
Which exon mutation is associated with worse clinical behavior in GISTs?
Exon 9 worse than exon 11 due to poor imatinib responsiveness
What are the three most important factors that independently predict recurrence of localized GIST?
Mitotic rate, tumor size, and tumor location
Preoperative assessment and staging of primary GIST
abd/pelvis CT scan + CXR
What care should be taken when operating on GISTs?
Avoid excessive tumor manipulation: can cause bleeding or rupture leading to seeding of the peritoneum
What margins are needed for GIST?
1-2 cm. GISTs displace rather than infiltrate adjacent structures
What did the ACSO Group Z9001 study show?
Adjuvent imatinib use for 3cm or larger GISTs demonstrated benefit in recurrence-free survival.
What are the side effects of imatinib?
Diarrhea, abdominal discomfort, dermatitis, periorbital or peripheral edema
Is there a role for neoadjuvent imatinib use for GIST?
Yes. Can down-size the tumor and effect nature of surgery a patient receives
What are the NCCN guidelines for CT follow-up following GIST resection?
3-6 months x 5 years, then annually thereafter
What is the medial time to recurrence for GIST?
18-24 months
What is the Cameron algorithm for GIST recurrence?
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.
