Adjuvant Imatinib for GI Stromal Tumors: When and For How Long?

A 45-year-old woman presented with syncope. She was severely anemic, with a hemoglobin level of 6 g/dL, and was found to have lower GI bleeding. A diagnostic colonoscopy was negative. A subsequent computed tomography scan of the abdomen and pelvis was performed, revealing a 3.2 × 3 × 2.9-cm contrast-enhancing right lower-quadrant mass arising from the wall of the ileum. There was no evidence of metastatic disease. The patient underwent laparotomy, and a 3.5-cm mass was resected with negative margins. Pathology revealed a GI stromal tumor with mixed spindle and epithelioid features involving the mucosa and submucosa (Fig 1A). The tumor cells were positive for CD117 (c-kit) (Fig 1B) and DOG-1(Fig 1C). There were eight to 10 mitoses per 50 high-power fields (Fig 1D). Molecular studies showed a 42-base pair deletion in exon 11 of the KIT gene that would delete all or part of codons 558 to 572 (V559_D572del) and would change the 558-encoding amino acid from Lys to Asn (K558N).