Inhibition of metabolic activity in papillary thyroid carcinoma by a somatostatin analogue.

Two patients with widely metastatic papillary thyroid cancer demonstrated progressive growth of diffuse pulmonary lesions. One patient had no apparent response to high doses of 131I and the other hand no 131I uptake. 111In-pentetreotide scans revealed that many of the metastatic lesions expressed somatostatin receptors. The baseline metabolic activity and three-dimensional volume of the lesions were determined by 18F-fluoro-de-oxyglucose positron emission tomography (FDG-PET). After 3 or 4 months of octreotide (Sandostatin LAR Depot; Novartis Pharmaceutical, East Hanover, NJ) therapy, repeat FDG-PET scans revealed reductions in tumor volume and decreases in the standard uptake values of FDG. We conclude that octreotide therapy can change the biological activity of metastatic thyroid cancer lesions that exhibit somatostatin receptors.