Indium-111-DTPA-octreotide scintigraphy modulation by treatment with unlabelled somatostatin analogue in small-cell lung cancer.

Aims And Background: Small-cell lung cancer (SCLC) tissue expresses somatostatin receptors and can be visualized by means of the indium-111-labelled somatostatin analogue DTPA-D-Pheoctreotide. The aim of the study was to investigate whether treatment with a cold somatostatin analogue can affect the imaging of somatostatin receptor scintigraphy.

Methods: Three patients with SCLC were treated with 200 micrograms of cold octreotide three times a day subcutaneously for 7 days. Whole body and planar scintigraphy was performed before and after the treatment.

Results: 111In-DTPA-octreotide uptake was increased in cancer lesions, whereas fixation in normal tissues (liver, spleen, kidneys) decreased.

Conclusions: This is the first demonstration of an enhancement of SCLC imaging following unlabelled somatostatin analogue administration. Similar results have been described by other authors in a limited number of carcinoid tumors.