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.