Recurrence of Gastric Gastrointestinal Stromal Tumor after R0 Reduction with Pathological Complete Response to Neoadjuvant Imatinib Therapy-A Case Report

A 68-year-old woman presented with an abdominal mass. Abdominal computed tomography(CT)revealed a tumor (167 mm in diameter)that originated from the posterior gastric wall, and was diagnosed as a gastric gastrointestinal stromal tumor(GIST)based on a fine-needle aspiration biopsy. Additionally, we observed a ground-glass opacity in the left upper lobe, which was suggestive of primary lung carcinoma. Positron emission tomography(PET)revealed no evidence of distant metastases. The patient received neoadjuvant imatinib therapy, causing a reduction in GIST size. Left upper lung lobectomy was performed following a 3 months imatinib administration, then an additional 4 months of imatinib therapy, which induced a partial response(reduction rate of 60%). Subsequently, the patient underwent partial gastrectomy, distal pancreatectomy, and splenectomy for elective complete tumor resection. Histopathological findings showed no viable tumor cells nor evidence of invasion of the surrounding organs. CT performed 17 months after tumor resection without adjuvant therapy(at the patient's request)revealed a single perineal metastatic lesion. Imatinib therapy was administered, and a PET-documented complete response was achieved at 10 months. The patient maintained a complete response for 65 months after imatinib reinitiation.