Gastrointestinal Stromal Tumor (GIST) : A Comprehensive Review


  • Is a tumor of mesenchymal origin (previously thought to be of smooth muscle origin)
  • Most common mesenchymal neoplasm of GI tract
  • Arise from interstitial cells of Cajal
  • Incidence: 7-15 cases per million per year
  • 95% overexpress KIT (CD117), 80% express BCL-2 and 70% express CD34
  • KIT negative GIST will express PDGFRA
  • Sites: stomach (40-60%), SI (20-40%), colon/rectum (5-15%)

Other facts:

  • Gastric GIST arise most commonly after 50 years
  • 5% of all GIST are associated with an underlying heritable mutation such as familial GIST syndrome (mutation in KIT and PDGFRA), NF-1, Carney-Stratakis syndrome (GIST+paraganglioma+/-pulmonary chondroma)
  • 2 pathological variants: spindle cell (70%)> epithelioid (30%)

Clinical features:

  • Non-specific symptoms: early satiety, bloating and vague abdominal pain
  • Bleeding: Malena or frank hematemesis
  • Tumor rupture with intra-abdominal hemorrhage is uncommon, but when it occurs, it requires urgent surgical intervention.


  • CECT with IV and oral contrast is the IOC: helps in diagnosis as well as staging of disease and is non-invasive
  • MRI is indicated only when there is contraindication of CT and for rectal GIST.
  • Staging of the disease is important especially when the patient is considered for neoadjuvant imatinib therapy.
  • PET-CT is the gold standard investigation for recurrent GIST.

Role of biopsy/tissue diagnosis in GIST (current consensus):

  • Is not recommended as it is a submucosal tumor (go for direct upfront surgery if there is high suspicion of GIST in imaging and the disease is operable)
  • If there is diagnostic dilemma then go for biopsy
  • EUS guided FNA is superior to UGI endoscopy guided biopsy as the tumor is submucosal.
  • Sensitivity and specificity of EUS guided FNA: 82% and 100% respectively


  • Mainstay of treatment: complete surgical excision
  • Indication of surgery: size >2 cm and symptoms
  • For tumors <2 cm:
    • If high risk features are present on endoscopy or EUS go for surgery
    • If not can be observed with 6-12 monthly EUS/endoscopy follow up

High risk features:

  • Irregular borders
  • Ulceration
  • Echogenic foci
  • Heterogeneity 

Choices of surgery:

  • Depending on tumor size and sites surgeries can vary from wide local excision, enucleation, sleeve gastrectomy, or total gastrectomy.

Aim of surgery:

  • R0 resection 
  • Lymph node dissection is not required as lymphatic metastasis is very rare 
  • Tumor should be handled carefully intraoperatively to avoid rupture or spillage.


  • 2 main prognostic factors:
    • Tumor size 
    • Mitotic rate
  • Based on long term follow up study of 1700 patients with Gastric GIST, malignant potential based on combination of these 2 factors have been established as shown below:
Malignant potentialComments Mortality 
Benign Size: up to 2 cmMitosis: up to 5/50 hpfNo tumor related mortality
Probably benignSize: 2-5 cmMitosis: same as above<3%
Uncertain/ low malignant potentialSize: up to 2 cmMitosis: >5/50 hpf
Low to moderate Size: >10 cm Mitosis: same as benignORSize: 2-5 cmMitosis: >5/50 hpf12-15%
High Size: 5-10 cm Mitosis: >5/50 hpfORSize: >10 cmMitosis: >5/50 hpf49-86%

Role of adjuvant therapy:

  • Drug of choice: imatinib (tyrosine kinase inhibitor)
  • Indication: metastatic disease, resectable but moderate to high-risk malignant potential
  • Can be used as neoadjuvant therapy if the disease is non-metastatic but unresectable.

Landmark trials in GIST:

  • ACOSOG Z9001 trial:
    • C-KIT positive tumors 3 cm or larger who underwent complete resection found that patients treated with imatinib for 1 year had significantly improved 1 year recurrence free survival (98% VS 83%).
  • Scandinavian Sarcoma group trial:
    • Compared adjuvant course of imatinib (36 months VS 12 months) after resection of high-risk GIST
    • Result: extended course (36 months) had higher 5-year RFS and OS.
    • This trial has established a 3-year course as the standard of care after resection of high-risk GIST.

Algorithm for management of GIST:

gist approach

Reference: Sabiston textbook of surgery 21st edition

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