A 65-year-old man with a GIST (gastrointestinal stromal tumor) of the stomach, 8 cm, is resected. Immunohistochemistry confirms CD117 (c-KIT) positive, CD34 positive, DOG1 positive. Mitotic count is 12/50 HPF. This tumor is classified as:

• A Low risk — surveillance only
• B High risk — adjuvant imatinib for 3 years ✓
• C Intermediate risk — imatinib for 1 year
• D Very high risk — combination imatinib + sunitinib

Explanation

GIST risk stratification (AFIP/Modified NIH criteria): gastric location, size >10 cm, mitotic count >10/50 HPF = high risk. This tumor (8 cm, 12 mitoses/50 HPF, gastric) is high risk per Joensuu criteria (>10 cm OR >10 mitoses/50 HPF = high risk). The ACOSOG Z9001 and SSG XVIII trials established adjuvant imatinib 400 mg/day for 3 years as standard of care for high-risk GIST, reducing recurrence-free survival events by 50% compared to 1 year. Mutational analysis (KIT exon 11 vs exon 9) guides imatinib dosing (400 mg vs 800 mg). Sunitinib is reserved for imatinib-resistant disease.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.