Doxorubicin and streptozotocin after failed biotherapy of neuroendocrine tumors

Background: Well-differentiated neuroendocrine tumors are treated primarily with somatostatin analogs and interferon-α. It is not clear what therapy should be applied after failed biotherapy. Our aim was to establish whether patients whose tumors rapidly progress under biotherapy may benefit from chemotherapy. Patients and Methods: In 10 patients with metastatic neuroendocrine tumors (4 foregut, 3 midgut, 1 retroperitoneal, and 2 of unknown origin) streptozotocin and doxorubicin were used as second-line or third-line therapy. Tumor response was assessed by computed tomography of the abdomen and thorax and measurement of tumor secretion products (serum chromogranin A, urinary 5-hydroxyindoleacetic acid). Results: Three patients showed a radiological response over a mean time of 30 mo (range: 7–67 mo). Median survival after initiation of chemotherapy was 50 mo in patients with a response and 8 mo in non-responders. Three patients developed major side effects (nephrotoxicity, diabetes, and encephalopathy). Conclusion: Streptozotocin and doxorubicin produce poor response rates in patients with progressive neuroendocrine tumors after failed biotherapy, but may prolong life in those patients who show a tumor response.