IN-111 OCTREOTIDE IMAGING IN STAGING OF SMALL-CELL LUNG-CANCER

Background: Small cell lung cancer (SCLC) tumors have neuroendocrine f eatures. In vitro and in vivo studies have demonstrated that 50%-75% o f SCLC tumors express receptors for somatostatin. This might enable in vivo localization of the primary tumor and its metastases by using sc intigraphy with a radiolabeled somatostatin analogue, such as octreoti de. Purpose and Methods: The efficacy of scanning with In-111 labeled octreotide (octreotide scan) was studied in the staging of SCLC patien ts and compared with the results of conventional staging (liver ECHO, bone scintigraphy, MRI of the brain, spine, and pelvis). Imaging was p erformed in 29 patients with histologically confirmed SCLC at 4, 24, a nd 48 hours after intravenous injection of 185 MBq In-111 octreotide. Results: In 24 of 29 patients, the primary tumor was visualized. In th ese 24 patients, 26 metastases were demonstrated with conventional sta ging, of which only nine were visualized with octreotide scan. Octreot ide scans showed two metastases in the brain that were not visualized by MRI. In the other five patients, five metastases were demonstrated with conventional staging. Only two of these were detected with octreo tide scan. However, octreotide scan did show a further metastasis in t he brain that was not visualized by MR imaging. Conclusion: Octreotide imaging has a limited use in the detection of SCLC metastases compare d to conventional staging. It might have some specific value in the de tection of brain involvement in patients with limited disease.