Background: 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.
Case report: 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.
Conclusion: This is the second report of metachronous prostate cancer, gastric cancer, and GIST in the English language literature.