technetium-tc-99m-depreotide and Carcinoma--Small-Cell

(177)Lu-DOTA-Tyr(3)-octreotate is a candidate radiopharmaceutical for the therapy of somatostatin receptor (sstr)-positive small cell lung cancer (SCLC). Scintigraphy of lung tumors is made with 2 alternative somatostatin analogs, (111)In-DTPA-octreotide or (99m)Tc-depreotide. The aim of this study was to compare the biodistribution of these 3 radiopharmaceuticals in SCLC xenografted to nude mice.. Nude mice, bearing tumors from the human SCLC cell line NCI-H69, were intravenously injected with 10 MBq (2.4 microg) (99m)Tc-depreotide and 2 MBq (0.5 microg) (111)In-DTPA-octreotide simultaneously. The activity concentration (%IA/g) was measured in tumor and normal tissue at 2, 4, and 24 hours postinjection (hpi). The results were compared with earlier published biodistribution data of 3 MBq (0.7 microg) (177)Lu-DOTA-Tyr(3)-octreotate in the same animal model.. The activity concentration of (111)In-DTPAoctreotide in tumor was higher than the activity concentration of (99m)Tc-depreotide at 2-24 hpi, p < 0.05. The highest tumor uptake at 24 hpi was, however, found for (177)Lu-DOTA-Tyr(3)-octreotate. The activity concentration of (99m)Tc-depreotide was significantly higher in the heart, lungs, liver, the salivary glands, spleen, and bone marrow than for (111)In-DTPA-octreotide at 2-24 hpi. Saturation of the somatostatin receptors may have influenced the uptake in tumor and sstr-positive normal tissues.. The low tumor-to-lung and tumor-to-liver activity concentration ratios for (99m)Tc-depreotide could result in a lower detection rate of SCLC with this compound versus (111)In-DTPA-octreotide. (177)Lu-DOTA-Tyr(3)-octreotate gave the highest tumor-activity concentration, and has, thus, the best properties for therapy.

Topics: Animals; Carcinoma, Small Cell; Cell Line, Tumor; Disease Models, Animal; Humans; Indium Radioisotopes; Liver; Lung; Lung Neoplasms; Mice; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental; Octreotide; Organometallic Compounds; Organotechnetium Compounds; Pentetic Acid; Radiopharmaceuticals; Somatostatin; Time Factors; Tissue Distribution

Topics: Carcinoma, Small Cell; Fluorodeoxyglucose F18; Humans; Lung Neoplasms; Organotechnetium Compounds; Radiopharmaceuticals; Receptors, Somatostatin; Somatostatin; Tomography, Emission-Computed

Topics: Aged; Aged, 80 and over; Biopsy; Carcinoma, Small Cell; Cell Transformation, Neoplastic; Diagnosis, Differential; False Positive Reactions; Fluorodeoxyglucose F18; Humans; Lung Neoplasms; Male; Organotechnetium Compounds; Radiopharmaceuticals; Somatostatin; Tomography, X-Ray Computed

The affinity of various malignant neoplasms including small cell and non-small cell lung cancer for peptide analogs of somatostatin has been well documented. Depreotide is such an analog and can be complexed with technetium-99m ((99m)Tc depreotide) for optimal imaging properties. Using this radiopharmaceutical, solitary pulmonary nodules (SPN) were previously evaluated in a successful phase II/III trial. The results of the larger multicenter phase III study using (99m)Tc depreotide to differentiate malignant and benign etiologies in SPN are now presented.. Patients with SPN 30 years, and no demonstrable radiographic stability for the prior 2 years were studied. All underwent single-photon emission CT (SPECT) with (99m)Tc depreotide and subsequent tissue histologic examination. Three nuclear medicine specialists blinded to histologic findings examined the SPECT images and scored them as positive or negative based on the presence or absence of activity in the radiographic region of the SPN. The final result was determined by the majority score, which was then compared with the histologic result.. Of the 114 individuals studied, 88 had a histologic result compatible with malignant neoplasm. (99m)Tc depreotide scintigraphy correctly identified 85 of this group, with three false-negative determinations compared with histology. There were seven false-positive determinations, including six granulomas and one hamartoma. (99m)Tc depreotide scintigraphy correctly excluded malignancy in 19 of 26 patients with benign histologic findings. The sensitivity of this method was 96.6% with a specificity of 73.1%.. (99m)Tc depreotide scintigraphy is a safe and useful method for the noninvasive evaluation of SPN with a sensitivity and accuracy comparable to that reported for fluorine-18 fluorodeoxyglucose positron emission tomography.

Topics: Aged; Carcinoma, Non-Small-Cell Lung; Carcinoma, Small Cell; Contrast Media; Diagnosis, Differential; Female; Humans; Image Enhancement; Intercellular Signaling Peptides and Proteins; Lung; Lung Diseases; Lung Neoplasms; Male; Middle Aged; Peptides; Predictive Value of Tests; Prospective Studies; Solitary Pulmonary Nodule; Somatostatin; Tomography, Emission-Computed, Single-Photon