Somatostatin receptor imaging in somatotroph and non-functioning pituitary adenomas: correlation with hormonal and visual responses to octreotide.
Clin Endocrinol (Oxf)
; 47(5): 589-98, 1997 Nov.
Article
in En
| MEDLINE
| ID: mdl-9425399
ABSTRACT
OBJECTIVE:
A multicentre study was undertaken to determine the value of somatostatin receptor (sst) scintigraphy in predicting hormonal and visual responses to octreotide treatment in GH-secreting and non-functioning pituitary adenomas. SUBJECTS ANDMETHODS:
Somatostatin receptor scintigraphy was performed in 48 patients (19 acromegaly, 29 non-functioning pituitary adenomas with ophthalmological defects). Results were expressed as an uptake index of the pituitary area. A threshold for positivity was determined in 23 subjects considered as controls. Thirty-five patients were treated for 1 month with octreotide (300 micrograms daily). The therapeutic response was assessed on GH and IGF-I suppression or evolution of the ophthalmological defects. The relationships between the somatostatin receptor scintigraphy result, the therapeutic effect of octreotide and in vitro studies performed in 12 tumours were studied.RESULTS:
From the results of control subjects the uptake index threshold for positivity was 2. In patients, somatostatin receptor scintigraphy was positive in 64% and there was no relationship between uptake index and tumour size. In GH tumours, somatostatin receptor scintigraphy was positive in 68%; uptake index was related to octreotide-induced GH and IGF I suppression. The positive predictive value was 100% and the negative predictive value was 50%. In vitro studies showed detectable binding sites for somatostatin with sst2 and sst5 expression in the 4 GH tumours studied although somatostatin receptor scintigraphy was negative in 2 cases. In non-functioning pituitary adenomas somatostatin receptor scintigraphy was positive in 62%. Based on visual effects, the positive predictive value was 61% and the negative predictive value was 100%. A wide distribution of somatostatin binding sites was found in 8 non-functioning pituitary adenomas with expression of sst2 only.CONCLUSION:
In the conditions of the study, in patients with acromegaly, positive somatostatin receptor scintigraphy predicts a hormonal response but the value of somatostatin receptor scintigraphy is limited by its low negative predictive value. In patients with non-functioning pituitary adenomas, negative somatostatin receptor scintigraphy predicts that there will be no visual improvement during octreotide treatment.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pituitary Neoplasms
/
Growth Hormone
/
Octreotide
/
Adenoma
/
Receptors, Somatostatin
/
Antineoplastic Agents
Type of study:
Clinical_trials
/
Prognostic_studies
Limits:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
Clin Endocrinol (Oxf)
Year:
1997
Document type:
Article
Affiliation country:
France