111In-octreotide scintigraphy in metastatic medullary thyroid carcinoma before and after octreotide therapy: in vivo evidence of the possible down-regulation of somatostatin receptors.
We have investigated the presence of somatostatin receptors on the cell surface of metastatic medullary thyroid carcinoma in vivo using 111In-Octreotide scintigraphy. Five patients were studied before and three months after therapy with octreotide (300-600 micrograms/day). After each 111In-Octreotide scintigraphy the target/background (T/B) radioactivity ratio was calculated for each detectable metastases. A total of 14/18 metastases showed a reduction in the T/B ratio after therapy, suggesting saturation or down-regulation of the somatostatin receptors on metastases induced by octreotide therapy. Patients also showed a reduction in serum calcitonin levels after therapy. We conclude that 111In-Octreotide scintigraphy may be useful in medullary thyroid carcinoma to evaluate the rationale for somatostatin therapy and to monitor the effect of treatment.
Ronga
G
G
Special Service of Nuclear Medicine, II Medical Clinic, University La Sapienza, Rome, Italy.
Salerno
G
G
Procaccini
E
E
Mauro
L
L
Annovazzi
A
A
Barone
R
R
Mellozzi
M
M
Tamburrano
G
G
Signore
A
A
D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D002116:Calcitonin / Q000097:blood; D018276:Carcinoma, Medullary / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000556:secondary*; D015536:Down-Regulation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007205:Indium Radioisotopes; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin / Q000032:analysis / Q000187:drug effects*; D004113:Succimer; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
D018931:Antineoplastic Agents, Hormonal; D007205:Indium Radioisotopes; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; C094279:indium-111-octreotide; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D002116:Calcitonin; D004113:Succimer; D015282:Octreotide