High-dose indium 111In pentetreotide radiotherapy for metastatic atypical carcinoid tumor.

Indium In 111 pentetreotide imaging of neuroendocrine tumors that overexpress somatostatin receptors has become standard for localization of these tumors. This radioligand is internalized into the cell and can induce receptor-specific cytotoxicity by emission of Auger electrons. We hypothesized that high-dose 111In-pentetreotide could be therapeutic in patients with somatostatin receptor-expressing tumors. Our 35-year-old patient had atypical carcinoid tumor metastatic to cervical, supraclavicular, mediastinal, and mesenteric lymph nodes and to the liver and bone. Chemotherapy had stabilized the disease but with severe gastrointestinal side effects. After a diagnostic 111In-pentetreotide scan, the patient was given eight courses (180 mCi each) of 111In-pentetreotide therapy to selectively target somatostatin receptor-expressing tumor cells. The disease was stable for approximately 14 months. The patient had two additional courses of 111In-pentetreotide therapy (360 mCi each). She died of the disease approximately 18 months after initiation of 111In-pentetreotide therapy.