Q1. True about the epidemiology of GIST
a) It is rare below 40 years of age with mean age being 60
b) Most of the GIST are familial
c) Association of GIST with Neurofibromatosis leads to tumor in stomach
d) Phenotypic variations can predict weather it is familial or sporadic.
Q2. Which is the most common organ of origin for Gastrointestinal stromal tumor (GIST)
Q3. Which of the following regarding GIST is not true?
a) FNAC is done routinely to establish the diagnosis of GIST
b) Imatinib has a role in presurgical settings
c) Previously most of the GISTs were called as leiomyomas
d) GIST is a relatively new name
Q4. Which of the following is not an option for Imatinib resistant GIST
a) Increase the dose to 800 mg/day
c) Chemotherapy with Cisplatin
d) Radiofrequency Abalation
- GISTs occur predominantly in middle-aged and older individuals, and rarely in those under the age of 40.
- Although the majority of GISTs appear to be sporadic, approximately 5 percent of patients have one of several familial autosomal dominant syndromes
- In the setting of NF1, GISTs are frequently in the small intestine (more than 70 percent)
- Phenotypic, histologic and molecular features appear to be indistinguishable in familial and sporadic cases
GIST are being recognized with increasing frequency now
Small bowel- 20-30%
10% - Esophagus, Colon, Rectum
Rarely- Omentum, Mesentary and Retroperitoneum
FNAC is not indicated routinely
GIST are Vascular lesions and Can bleed profusely.
There is also
-Risk of tumor rupture
-Seeding along the needle tract
-Peritoneal or mesenteric contamination
FNAC only indicated in unresectable lesions to make the diagnosis and start preoperative Imatinib
Imatinib resistance can develop after long-term treatment. In patients who have GIST that progresses while taking imatinib at a dose of 400 mg/day, the dose can be escalated to 800 mg/day. Five percent of patients who progress at 400 mg/day will respond to the elevated dose of imatinib and achieve at least partial remission.In patients who have imatinib-resistant GIST or who do not tolerate imatinib, sunitinib is the next line of therapy. It is a multitargeted tyrosine kinase inhibitor that has both antitumor and antiangiogenic abilities. Its mechanism involves inhibition of vascular endothelial cell growth factor receptors 1, 2, and 3; KIT; PDGFR?; PDGFRß; Fms-like tyrosine kinase-3 receptor; and the ret proto-oncogene receptor. The results of treatment with traditional chemotherapy have not been successful. Less than 10% response rate.
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