Abstract
RATIONALE: The problem of the coexistence of gastrointestinal stromal tumor (GIST) with other neoplasms is complex, and carcinomas of prostate is one of the common types of GIST-associated cancers. Doubling time of GIST is about 3.9 months for high-risk GIST, and the treatment paradigm for GIST has required the integration of surgery and molecular therapy. PATIENT CONCERNS: A 70-year-old man with postoperative history of prostate cancer experienced fast-growing malignant jejunal GIST with multiple peritoneal metastases within 1 year. DIAGNOSES: Enhanced computed tomography (CT) detected a neoplasm of small intestine with multiple peritoneal nodules and postoperative pathology confirmed GIST. INTERVENTIONS: Oral imatinib after surgery, at 400 mg per day, was used for 4 years. OUTCOMES: The patient remains well, and the peritoneal nodules located in front of the rectum disappeared gradually. LESSONS: Physicians should be aware of possibility of GIST in patients with prostate cancer and can perform abdominal examination in these patients. For postoperative patients with prostate cancer, an yearly or half-yearly abdominal and pelvic cavity examination can be performed. Suspicion and timely work-up is necessary in these postoperative prostate cancer patients, especially when they have abdominopelvic pain.