111In-octreotide scintigraphy in small cell lung cancer.

Somatostatin receptors have been identified on the cellular surface of a subset of patients with small cell lung cancer (SCLC) and may be associated with a less aggressive evolution of the tumor. Moreover, medical therapy with somatostatin analogues holds promise for neoplastic growth control. We performed planar imaging in 22 patients with histologically proven SCLC at 2-4 and 24 hours after the injection of 111-185 MBq of 111In-DTPA-octreotide (Octreoscan, Byk-Gulden). Tumor uptake was observed in 19 patients in both early and late scans, while 2 patients previously treated with chemotherapy showed negative early and late scans. One patient had a positive early scan and a negative late scan. All the scintigraphic studies showed more extensive disease than expected by CT. No significant modification in tumor uptake of radiooctreotide was observed in three patients studied before and after chemotherapy. In conclusion, 111In-octreotide is a suitable radiopharmaceutical for the in vivo evaluation of the somatostatin receptors of small lung cancer. The prognostic and therapeutical implications of this nuclear technique must be further investigated, however.