High-dose indium In-111 pentetreotide radiotherapy for metastatic atypicalcarcinoid tumor

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