Secondary tumors of the GI tract: origin, histology, and endoscopic findings.

BACKGROUND AND AIMS: The GI tract is rarely affected by secondary tumors. Patients often present at an advanced stage of the disease, and prognosis is dismal. This study aimed to analyze the clinical, endoscopic, and pathologic features of secondary tumors that had been diagnosed endoscopically. METHODS: We conducted a retrospective database analysis of 217 patients with secondary tumors of the GI tract. Endoscopic findings and histologic diagnoses were systematically re-evaluated. RESULTS: Malignant melanoma (n = 33, 15%), breast cancer (n = 32, 15%), and pancreatic cancer (n = 27, 12%) were the most common corresponding primaries. About one-third of secondary tumors were detected in the stomach (n = 76, 35%), followed by small intestine (n = 54, 25%) and rectum (n = 53, 24%). The median time between the diagnoses of primary and secondary tumors was 19 months (mean, 31; range, 0-251), and this time was particularly long for renal cell carcinoma and breast cancer (median, 38 and 45 months, respectively). Direct invasion from extra-GI malignancies was more common (56%) than vascular cancer spread (44%) and depended on both sites of tumor involvement and corresponding primary. The lesions presented with various endoscopic patterns. In patients for whom a definitive diagnosis of cancer was known before the examination (n = 168), a secondary tumor was included in the differential diagnosis in only 48% of lesions. It is of note that the remaining cases were diagnosed endoscopically as primary tumors and rarely also as nonneoplastic change. CONCLUSIONS: Secondary tumors may affect all parts of the GI tract. Malignant melanoma and breast and pancreatic cancer represent the most common primaries. Diagnosis based on examination of biopsy specimens is crucial to avoid misclassification.