RADIOIODINATED SOMATOSTATIN ANALOG SCINTIGRAPHY IN SMALL-CELL LUNG-CANCER

Somatostatin receptors have been characterized on biopsy specimens from small-cell lung carcinoma (SCLC) and on cultured human SCLC cells. We recently described the in vivo visualization of various somatostatin receptor-positive tumors, such as carcinoids and endocrine pancreatic tumors, after injection of I-123-Tyr-3-octreotide, a radiolabeled somatostatin analog. In the present study, this imaging procedure using I-123-Tyr-3-octreotide is reported in 11 patients with lung tumors. In five of eight patients with SCLC (63%), we were able to demonstrate tumor deposits using I-123-Tyr-3-octreotide scintigraphy. Unexpected metastases were found in two patients. In one of three patients with SCLC in whom tumor was not visualized, nonvisualization may have been caused by tumor necrosis and recent radiotherapy. In one of two patients with malignant small-cell tumors as described by Askin, the neoplasm was visualized. Like SCLC, these tumors are thought to derive from neuroendocrine cells. In one patient, a squamous-cell carcinoma and a bronchial adenoma were not visualized. We conclude that in the majority of patients with SCLC, the tumor and its metastases can be visualized using I-123-Tyr-3-octreotide scintigraphy. However, the value of this new technique in terms of specificity and sensitivity requires further studies in a larger group of patients.