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Gastrointestinal Stromal Tumors Treatment (PDQ®): Treatment - Health Professional Information [NCI] - General Information About Gastrointestinal Stromal Tumors Treatment

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Approximately 85% of GIST contain oncogenic mutations in one of two receptor tyrosine kinases: KIT or PDGFRA (platelet-derived growth factor receptor alpha).[2,10] Constitutive activation of either of these receptor tyrosine kinases plays a central role in the pathogenesis of GIST.[15,19] Wild-type tumors, with no detectable KIT or PDGFRA mutations, account for 12% to 15% of all GIST. Fewer than 5% of GIST occur in the setting of syndromic diseases, such as neurofibromatosis type 1 (NF1), Carney triad syndrome, and other familial diseases.[2,20,21,22] The correct identification of GIST is very important because of the availability of specific, molecular-targeted therapy with KIT/PDGFRA tyrosine kinase inhibitors (TKI) such as imatinib mesylate or, in the case of imatinib-resistant GIST, sunitinib malate.[1,10,17]

Risk Assessment and Prognosis

At the time of clinical presentation, the prognosis appears to be influenced by genetic events other than kinase mutations, although a particular kinase mutation may help to define the initial clinical course of a GIST. Based on retrospective studies from time periods that predated the clinical use of kinase inhibitors, current recommendations for assessing the risk of progression for a newly diagnosed primary GIST rely on three parameters (see Table 1):[2,23,24,25,26]

  • Mitotic index (mitoses per 50 high-power fields).
  • Tumor size.
  • Tumor location.

Table 1. Risk Stratification of Primary GIST by Mitotic Index, Tumor Size, and Tumor Locationa

GIST = gastrointestinal stromal tumors; hpf = high-power field, assessed from an area that on initial screen appears to have the highest mitotic activity.
a Annual review of pathology by ANNUAL REVIEWS, INC. Reproduced with permission of ANNUAL REVIEWS, INC., in the format Internet posting via Copyright Clearance Center.[2]
b Small numbers of cases.
Mitotic Index, hpfSize, cmSite and Risk of Progressive Disease (%)
  GastricDuodenumJejunum/IleumRectum
≤5 per 50≤2None (0)None (0)None (0)None (0)
>2 ≤5Very low (1.9)Low (4.3)Low (8.3)Low (8.5)
>5 ≤10Low (3.6)Moderate (24)(Insufficient data)(Insufficient data)
>10Moderate (10)High (52)High (34)High (57)
>5 per 50≤2NoneHighb(Insufficient data)High (54)
>2 ≤5Moderate (16)High (73)High (50)High (52)
>5 ≤10High (55)High (85)(Insufficient data)(Insufficient data)
>10High (86)High (90)High (86)High (7)

Compared to other intra-abdominal sarcomas, survival in GIST patients after surgery alone is favorable.[27] In a retrospective study involving 200 patients that predated the use of TKI, the 5-year disease-specific survival rate for GIST patients with primary disease who underwent complete resection of gross disease (N = 80) was 54%, with survival predicted by tumor size; the overall disease-specific survival was 35% at 5 years.[11] Other studies, which also predated TKI, reported 5-year survival rates of 40% to 63% for patients undergoing complete resections of GIST.

1|2|3|4

WebMD Public Information from the National Cancer Institute

Last Updated: February 25, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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