Gastric and Prostate Adenocarcinoma in a Patient with Metastatic Gastrointestinal Stromal Tumor

Abstract
Gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the gastrointestinal tract. Gastric cancer is the second most common neoplasm worldwide. Prostate cancer is the most common non-cutaneous cancer. The most frequently encountered second malignancies in patients with prostate adenocarcinoma include carcinomas of the bladder, stomach, and colon, followed by cutaneous and hematolymphoid malignancies. We report the case of a 60-year-old male patient who was diagnosed with GIST and started on imatinib mesylate 400 mg/day. 2 years later, the patient was diagnosed with gastric adenocarcinoma, and a subtotal gastrectomy and gastrojejunostomy were performed. At followup 6 months later, prostate-specific antigen (PSA) levels were elevated, and a prostate biopsy showed a prostate adenocarcinoma. This is the second report of metachronous prostate cancer, gastric cancer, and GIST in the English language literature.