(dtpa-phe(1))-octreotide and Malignant-Carcinoid-Syndrome

Radiolabeled somatostatin analogs have shown uptake in a variety of tumors. These include carcinoid, Merkel cell carcinoma, pheochromocytoma, islet cell tumor, and other tumors with somatostatin receptors. Radiolabeled somatostatin analog imaging with Indium-111-DTPA-pentetreotide permits whole body imaging, providing a new safe and effective means for detection of primary tumors and metastatic foci in neoplasms with somatostatin receptors. This imaging modality is helpful in screening the entire body as well as evaluating questionable foci of disease identified by conventional imaging modalities. This case report demonstrates the utility of computed tomography (CT) and radiolabeled somatostatin imaging as complementary modalities in the workup of a patient with metastatic carcinoid tumor.

Topics: Aged; Carcinoid Tumor; Female; Humans; Indium Radioisotopes; Intestinal Neoplasms; Intestine, Small; Liver Neoplasms; Malignant Carcinoid Syndrome; Octreotide; Pentetic Acid; Radionuclide Imaging; Radiopharmaceuticals; Receptors, Somatostatin; Somatostatin; Tomography, X-Ray Computed

A 55-yr-old woman with a midgut carcinoid syndrome due to metastatic spread of an ileal tumor to the liver, paraortic and mediastinal lymph nodes and to the skeleton was given systemic radionuclide therapy with 111In-DTPA-D-Phe1-octreotide. Before therapy, dosimetric calculations were performed on whole-body scintigraphs and 111In retention was shown to be long-lasting. Excretion was mainly seen during the first 24 hr after injection; thereafter whole-body retention remained stationary at 30%. Indium-111 activity in tumor biopsies and blood was measured using a gamma counter. Very high tumor-to-blood ratios were obtained: 150 for the primary tumor and 400-650 for liver metastases, which further justified radiation therapy. Indium-111-DTPA-D-Phe1-octreotide treatment was given on three separate occasions (3.0, 3.5 and 3.1 GBq) 8 and 4 wk apart. After each therapy, the patient experienced facial flush and pain over the skeletal lesions followed by symptomatic relief, even though no objective tumor regression was found radiologically after 5 mo. After initiation of octreotide treatment, there was a 14% reduction of the main tumor marker, urinary 5-HIAA. After three subsequent radionuclide therapies, there was a further 31% reduction of 5-HIAA levels. No adverse reactions, other than a slight decrease in leukocyte counts, were seen. The mean absorbed radiation dose after the three treatments was estimated to be about 10-12 Gy in liver metastases and 3-6 Gy in other tumors, depending on the size and location of the metastases. Assuming internalization of 111In into tumor cells and a radiobiological effect from short range Auger and conversion electrons, there might be a therapeutic effect on the tumor.

Topics: Female; Humans; Hydroxyindoleacetic Acid; Indium Radioisotopes; Malignant Carcinoid Syndrome; Middle Aged; Octreotide; Pentetic Acid; Radionuclide Imaging; Radiotherapy Dosage; Tomography, X-Ray Computed