SOMATOSTATIN RECEPTOR IMAGING IN SMALL-CELL LUNG-CANCER USING IN-111 DTPA-OCTREOTIDE - A PRELIMINARY-STUDY

Small cell lung cancer is a common and aggressive disease. Combined mu ltiagent chemotherapy and radiotherapy can improve short-term prognosi s, but long-term prognosis remains dim. Somatostatin receptors have be en identified on the cellular surface of subsets of this cancer and ma y be associated with less aggressive evolution. Moreover, medical ther apy with somatostatin analogues holds promise for neoplastic growth co ntrol. Planar scintigraphy has been performed in 15 patients with hist ologically proven small cell lung cancer at 4 and 24 h after the intra venous (i.v.) injection of 185 MBq In-111-octreotide (Octreoscan, BYK- Gulden). No short-term adverse effects were recorded; tumour uptake of the radiopharmaceutical was observed in 13 patients at 4 h and in 12 patients at 24 h suggesting more extensive disease than apparent by co mputed tomography (CT). It is highly likely that the 24 h uptake refle cts the presence of somatostatin receptors on the tumour. Previous che motherapy does not seem to play a key role in tumour visualization. In -111-octreotide is a suitable radiopharmaceutical for in vivo evaluati on of somatostatin receptor status of small cell lung cancer. Quantita tive scintigraphic methods are needed to investigate nonspecific bindi ng and receptor kinetics.