gastrointestinal stromal tumors
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Gastrointestinal Stromal Tumors. Definition of Gastrointestinal Stromal Tumor . the most common mesenchymal malignancy of (GI) tract the diagnostic criteria for GIST remained controversial and somewhat confusing. Pathology Terms that Encompass the Spectrum of Gastrointestinal Stromal Tumors. - PowerPoint PPT PresentationTRANSCRIPT
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Gastrointestinal Stromal Tumors
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Definition of Gastrointestinal Stromal Tumor the most common mesenchymal
malignancy of (GI) tractthe diagnostic criteria for GIST
remained controversial and somewhat confusing
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Pathology Terms that Encompass the Spectrum of Gastrointestinal Stromal Tumors Gastrointestinal stromal tumor
Leiomyoblastoma
Gastrointestinal leiomyosarcoma
Gastrointestinal autonomic nerve tumor
Gastrointestinal pacemaker cell tumor
Plexosarcoma
Gastrointestinal neurofibrosarcoma
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KIT expression is noted in the vast majority (more than 95%) of GISTs,
KIT is not expressed by other smooth muscle tumors of the GI tract nor by other stromal tumors outside of the GI tract
The origin of the neoplastic cells of GIST remains a matter of active investigation
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the KIT protein serves as a transmembrane RTK; the CD117 antigen can be detected by immunohistochemical staining as a marker for the presence of the KIT protein
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Clinical Considerationsadults at a median age of 58 years higher in men (60% to 70%) stomach, (20% to
30%) small intestine, and fewer than 10% in the esophagus, colon, and rectum. GISTs can also occur in extraintestinal abdominopelvic sites such as the omentum, mesentery, or retroperitoneum.
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abdominal painabdominal mass, nausea, vomiting, anorexiaweight loss. acute hemorrhage
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The vast majority of GIST metastases at presentation are intra-abdominal, either to the liver, omentum, or peritoneal cavity.
Metastatic spread to lymph nodes or to extra-abdominal sites via lymphatics is very rare
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Diagnostic Evaluation CTMRIupper GI endoscopyUltrasonographically enhanced
endoscopy
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an epithelioid (larger, rounder cells) or spindle cell histology.
expert pathologists can define a rare subset (fewer than 5%) of GISTs that fail to express CD117, and these are most likely to be driven by an alternative kinase such as PDGFRA
There are no definitive diagnostic criteria of CD117-GIST unless the tumor genotype analysis indicates a KIT or PDGFRA mutation characteristic of GIST
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DDXsoft tissue sarcomasEwing's sarcoma and angiosarcomasmall cell lung cancers, melanomas desmoid tumorsseminomas, ovarian carcinomas, mastocytomas, neuroblastomas, adenoid cystic carcinomas,subsets of lymphoma and acute myeloid
leukemia.
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Metastatic
Or un resecta
ble
h risk I risk low risk Very low risk
اندازه و اندازه هرمیتوز
از بیشتربا 5یا 10
متیوز یا متوسط
زیاد
از 3کمتر 5تا 2بین از 2کمترسانتیمتر
میزان میتوز
متوسط کم کم
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some contribution to prognosisOther factors, such as the specific
histologic subtype (epithelioid vs. spindle cell), the degree of cellular pleomorphism, and patient age,
Recurrence and survival rates have been reported to correlate with the location of the primary GIST lesion, with small bowel tumors showing a somewhat worse prognosis
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Diagnostic Imaging PETFDG-PET imaging can detect
lesions at least 1 cm
CT MRI
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Management of Metastatic, Unresectable, or Recurrent Gastrointestinal Stromal TumorCht: P-glycoprotein (the product
of the multidrug resistance-1 [MDR-1] gene) and the multidrug resistance protein-1 MRP1
RT: bleeding , pain
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First Molecularly Targeted Kinase Inhibitor Therapy for Gastrointestinal Stromal Tumor: Imatinib Mesylate
FDA approved the use of imatinib for the treatment of metastatic or unresectable GIST
objective responses control of symptoms prolonging the survival
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FDA approval of imatinib for dermatofibrosarcoma protuberans
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toxicitiesnausea, vomiting, and severe edema,diarrhea myalgia or musculoskeletal pain skin rashes headache MyelotoxicityCardiotoxicityhemorrhagic events tachyphylaxis
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18FDG-PET represents a useful diagnostic technique for very early assessment of response to imatinib therapy.
The optimal dose of imatinib for treatment of advanced GIST remains uncertain
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some marginal benefit might be obtained from modest dose escalation of imatinib in a subset of patients whose disease progresses despite continued dosing at lower therapeutic levels of imatinib
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The optimal duration of imatinibcontinued dosing with imatinib as
long as the disease is not progressive
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disease that is initially judged as unresectable may become amenable to surgical excision after a major response induced by imatinib therapy. Most centers recommend surgical resection for such patients because it is feared that residual GIST may develop secondary mutations that could result in clinical resistance to imatinib and progression of disease
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sunitinib definitely improved the progression-free survival of patients following imatinib failure due to resistance or intolerance
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Definitive expert surgery remains the mainstay of treatment for patients with localized, primary GIST
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Adjuvant Therapy to Improve Outcomes for Patients with Resected Early Stage The standard of care after
complete surgical resection of GIST has therefore been observation alone