In vivo somatostatin receptor imaging in medullary thyroid carcinoma.
Using in vivo scintigraphy with the 111In-labeled somatostatin analog octreotide, tumor localizations were demonstrated in 11 of 17 patients (65%) with medullary thyroid carcinoma (MTC). Tumor localizations in the liver in 7 patients, and in the thyroid in 1 patient were not detected on octreotide scintigraphy, most probably because of normal uptake of labeled octreotide in these organs. Specific somatostatin receptors were demonstrated in vitro on all 5 investigated tumors which had also been visualized in vivo, as well as on 1 tumor that was not. Immunohistochemically, somatostatin was present in 1 of 6 tumors that were visualized in vivo, and in neither of 2 tumors that were not. The ratio of serum calcitonin over carcino-embryonic antigen concentrations was significantly higher in patients whose MTCs were visualized during octreotide scintigraphy than in those whose tumors were not. We have formed the following conclusions: 1) In the majority of patients with metastatic MTC, tumor sites can be visualized using octreotide scintigraphy, although this technique is insensitive in detecting liver metastases or intrathyroidal tumor; 2) The visualization of MTC during in vivo somatostatin receptor imaging correlates with the in vitro presence of somatostatin receptors; 3) The immunohistochemical presence of somatostatin in the tumor does not seem to influence the outcome of in vivo somatostatin receptor imaging; and 4) Higher serum calcitonin over carcino-embryonic antigen ratios in patients whose MTC is visualized during octreotide scintigraphy might imply that somatostatin receptors are present on more differentiated MTC.
Department of Nuclear Medicine, University Hospital Dijkzigt, Rotterdam, The Netherlands.
D J
DJ
Kwekkeboom
J C
JC
Reubi
S W
SW
Lamberts
H A
HA
Bruining
A H
AH
Mulder
H Y
HY
Oei
E P
EP
Krenning
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001345:Autoradiography; D002116:Calcitonin / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D002277:Carcinoma / Q000097:blood / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000378:metabolism*
D002272:Carcinoembryonic Antigen; D017481:Receptors, Somatostatin; D002116:Calcitonin; D015282:Octreotide