Effects of preoperative octreotide treatment on different subtypes of 90 GH-secreting pituitary adenomas and outcome in one surgical centre.

OBJECTIVE: To investigate the possible impact of pretreatment with octreotide on different subtypes of GH-secreting pituitary adenomas and on the outcome of transnasal surgery.
METHODS: We reviewed a consecutive series of 90 acromegalic patients treated with octreotide alone before transnasal surgery. On the basis of magnetic resonance imaging, the tumours were classified into four groups: group A, microadenoma (n=7); group B, transnasally resectable macroadenoma (n=21); group C, invasive, potentially transnasally resectable macroadenoma (n=43); group D, non-resectable grossly invasive macroadenoma (n=19). All patients were treated for at least 3 months before surgery, with a mean daily dose of 221+/-31 microg octreotide. The mean follow-up was 51.7+/-1.4 months. The comparative group included 57 acromegalic patients who were not receiving octreotide treatment.
RESULTS: After pretreatment with octreotide, tumour shrinkage was clearly observed in 28 of the 90 patients (31%). At surgery, the tumours after octreotide treatment were more often white or grey in colour (91% compared with 75%) and were observed to be slightly more often fluid or soft in texture (86% compared with 79%) than those in the comparative series. Endocrinological remission was achieved in all patients in group A, 95.2% in group B, and 81.4% in group C. In only 10 of the 14 patients with tumour shrinkage in group C, endocrinological remission was also achieved (71.4%). In the comparative series, endocrinological remission was achieved in 92.9% of group A, 87.5% of group B, and 73.9% of group C.
CONCLUSIONS: Octreotide treatment slightly improved the already relatively high rate of endocrinological remission in invasive, potentially transnasally resectable macroadenomas. The rate of tumour shrinkage was found to decrease with extrasellar size. With the exception of tumour growth in approximately 7% of invasive adenomas and pituitary apoplexy in one patient, there was no disadvantage associated with the octreotide pretreatment.