Indium-111 activity concentration in tissue samples after intravenous injection of indium-111-DTPA-D-Phe-1-octreotide.

METHODS

Indium-111 activity concentrations in human tumor and normal tissue samples were determined at 24, 48 and 120 hr after i.v. injection of 111In-DTPA-D-Phe-1-octreotide. Fourteen patients were included in the study. Seven patients had medullary thyroid carcinoma, four had midgut carcinoid tumors, two had endocrine pancreatic tumors and one had chronic pancreatitis.

RESULTS

For midgut carcinoids, the tumor-to-blood ratio was 51:220, for medullary thyroid carcinoma 4:39, and for two endocrine pancreatic tumors 6 and 1500. Tumor-to-muscle ratios varied between 1 and 1200 and tumor-to-fat between 2 and 1500 depending on tumor type.

CONCLUSION

The sometimes extremely high tumor-to-normal tissue ratios present the possibility for use of radiolabeled octreotide for radiation therapy of somatostatin receptor positive tumors.