Treatment of invasive growth hormone pituitary adenomas with long-acting somatostatin analog SMS 201–995 before transsphenoidal surgery

Abstract

The purpose of this study was to determine whether the long-acting somatostatin analog SMS 201-995 (octreotide) shrinks growth hormone (GH)-secreting adenomas and improves the results of subsequent transsphenoidal surgery. Ten previously untreated active acromegalic patients (nine women and one man) with invasive tumors were treated with SMS 201-995 (100 micrograms subcutaneously every 8 hours) for 6 weeks prior to transsphenoidal surgery. The clinical activity, mean GH secretion, insulin-like growth factor (IGF)-I concentration, and tumor volume were measured under basal conditions and on Days 14, 28, and 42 of treatment. The SMS 201-995 improved the symptoms of acromegaly in all patients. Mean levels of both GH and IGF-I (+/- standard deviation) were significantly decreased by Day 14 (from 92.9 +/- 30.5 to 44.9 +/- 20.3 micrograms/liter and from 10.6 +/- 7.4 to 5.9 +/- 2.6 U/ml, respectively), after which there were only slight further decreases. Six (60%) of the 10 patients experienced tumor shrinkage ranging from 9% to 78% (mean 30%). When it occurred, tumor shrinkage was significant by Day 14 (7.9 +/- 6.3 to 6.5 +/- 5.1 cu cm) and no further shrinkage was achieved by longer administration. Transsphenoidal surgery reduced postoperative GH levels to less than 2 micrograms/liter and IGF-I to less than 1.5 U/ml in six patients (60%). This percentage of cure is higher than expected from the literature and the authors' previous experience. However, an investigation of the influence of this drug on several parameters, such as reduction of tumor size or GH and IGF-I concentrations, has failed to prove any relationship. Only pretreatment size of the tumor was of predictive value with respect to the surgical outcome.

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

“…Several studies have suggested that pretreatment with octreotide improved the results of transsphenoidal surgery in acromegaly (7, 8, 11, 16±18). Conversely, other authors have observed no signi®cant difference in surgical results between octreotide-pretreated patients with invasive adenomas and those who did not receive octreotide before surgery (7,8,12,19,20). However, with two exceptions (7,8), these reported series have included too few patients to permit de®nitive conclusions to be drawn for subtypes of different tumours.…”

“…To date, a limited number of authors have reported surgical ®ndings in patients who received octreotide treatment before surgery (7,8,12,16,17,20,29). We observed a soft consistency of adenomatous tissue in 85.6% of the 90 patients who received octreotide treatment and in 78.9% of the 57 comparative patients.…”

Effect of presurgical long-acting octreotide treatment in acromegaly patients with invasive pituitary macroadenomas: a prospective randomized study

“…On the other hand, low resection rates of the invasive macroadenomas are reported [5,24]. As indicated by several reports, presurgical long-acting octreotide decreases tumor volume [15,16,[25][26][27][28][29], and so presurgical long-acting octreotide should have greater therapeutic value, if the drug relieves the macroade- resolve this important management question for acromegaly.…”

Short-term Preoperative Octreotide Treatment of GH-secreting Pituitary Adenoma: Predictors of Tumor Shrinkage

“…Recent studies have shown that preoperative octreotide treatment is beneficial in some but not all types of macroadenoma [13,15]. Although reducing the size of GH-secreting adenoma by octreotide is thought to improve surgical results, the effect of octreotide treatment on tumor volume is unpredictable and is not correlated with its endocrinologic effects [9,10,18,20].…”