DTIC therapy in patients with malignant intra-abdominal neuroendocrine tumors

Malignant intra-abdominal neuroendocrine tumors are rare; consequently, a standard chemotherapeutic protocol for patients with unresectable disease has not been established. This prompted a review of our experience with dimethyltriazeno imidazole carboxamide (dacarbazine) (DTIC) treatment for these tumors. From 1976 to 1986, 14 patients were treated with DTIC for metastatic neuroendocrine tumors. There were seven men and seven women whose ages ranged from 19 to 76 years. Diagnoses included eight nonfunctioning islet-cell carcinomas, three retroperitoneal neuroendocrine tumors, two glucagonomas, and one ileal carcinoid. Before DTIC chemotherapy, four patients were treated with streptozotocin and 5-FU, and one was treated with cytoxan and methotrexate without response. Two patients who were initially treated with DTIC with no response were subsequently treated with streptozotocin and 5-FU without benefit. Standard treatment with DTIC consisted of monthly cycles of 250 mg/m2/day administered intravenously for 5 days. Seven patients had an objective response to DTIC with both improvement in quality of life and a decrease of more than 50% in tumor size on computerized tomography (CT) or liver scanning. Response duration ranged from 1 to 10 years. One patient with a glucagonoma was treated for two years and had no evidence of disease at laparotomy 7 years later. Four patients with nonfunctioning islet cell carcinoma had a positive response to DTIC, but three of these patients had tumor recurrence 3 to 6 years after treatment. Two patients with retroperitoneal neuroendocrine tumors had a positive response to DTIC treatment. One patient with a glucagonoma and one with a nonfunctioning islet-cell tumor had equivocal responses with transient clinical improvement but no objective changes in tumor size. Five patients did not respond; two were given DTIC therapy as a last resort and died 1 and 12 days later. Of the other three patients, two died 6 months and one 2 years after treatment. DTIC chemotherapy was effective in 50% of patients with intra-abdominal neuroendocrine tumors. Although DTIC therapy was associated with nausea, no major gastrointestinal, hematologic, or renal complications were noted. This favorable experience with DTIC chemotherapy for nonresectable intra-abdominal neuroendocrine tumors indicates that further clinical evaluation and use are warranted.