Synonyms

GIST

Category

Soft tissue

Behaviour

Intermediate

Grade

Variable

Gender

Both equally

Tissue of Origin

Other

Epidemiology

• KIT-driven mesenchymal tumour
• Peak incidence 5th-6th decades
• Predilection for stomach (60%) and small bowel (30%)
• Risk stratification by size and mitotic rate
• Familial GIST rare

Clinical Features

• GI bleeding (haematemesis or melena)
• Abdominal pain or mass
• Anaemia
• Constitutional symptoms if advanced

Location

• Stomach (most common)
• Small bowel
• Colon
• Rectum
• Mesentery/omentum

Imaging

• CT: submucosal mass
• MRI: assess local extent
• Hemorrhage and necrosis common in large lesions

Pathology

• Spindle cells (70%), epithelioid (20%), or mixed (10%)
• KIT+ (CD117+) and DOG1+ defining markers
• KIT exon 11 or 9 mutations common
• Risk stratification: size and mitotic rate

Genetics

• KIT mutations 95%
• PDGFRA mutations in 5%
• Rare WT-GIST (wild-type, SDHA/B mutations)

Treatment

• Surgical resection: primary for localized disease
• Imatinib (TKI): neoadjuvant for large/borderline-resectable
• Imatinib adjuvant: intermediate and High-risk lesions
• Sunitinib or regorafenib: imatinib-resistant metastatic

Prognosis

• 5-10% recurrence for small Low-risk; 50%+ for large High-risk
• Metastatic: improved with tyrosine kinase inhibitor therapy
• KIT mutation type prognostic

Key Points

• KIT mutations define GIST
• Risk stratification guides treatment
• Tyrosine kinase inhibitors transforming prognosis

Workup - Blood Tests

FBC, U&E, LFTs

Workup - Local Imaging

• CT abdomen/pelvis: local and metastatic staging
• Consider endoscopy: gastric lesions
• EUS: assess resectability

Workup - Biopsy

• Core biopsy: KIT and DOG1 immunostains
• KIT mutation analysis: prognostic and therapy

Workup - Staging

CT chest/abdomen/pelvis

Workup - Other

• Multidisciplinary planning for large/borderline-resectable
• Neoadjuvant imatinib for large lesions
• Adjuvant imatinib for intermediate/High-risk

Follow-up Summary

• Follow-up dependant on grade
• Low risk:
• Year 1: CT abdomen/pelvis ± CXR at 12 months post-surgery. Then discharge.
• High risk:
• Years 1–2: 3-monthly clinical examination and CT abdomen/pelvis ± CXR
• Years 3–4: 6-monthly clinical examination and CT abdomen/pelvis ± CXR
• Years 5–10: Annual clinical examination; annual CT abdomen/pelvis ± CXR Year 5 only, then stop
• Discharge at 10 years after surgery