PREOPERATIVE TREATMENT OF GROWTH HORMONE-PRODUCING PITUITARY-ADENOMA WITH CONTINUOUS SUBCUTANEOUS INFUSION OF OCTREOTIDE

Preoperative therapy with octreotide, a long-acting somatostatin analo g, suppresses GH hypersecretion, shrinks GH-producing tumors and leads to an improvement in subsequent surgical remission in acromegalic pat ients. A continuous infusion of octreotide has demonstrated more persi stent suppression of GH secretion than intermittent injections, and on ly a few studies were reported on the effect of the tumor shrinkage wi th a continuous infusion of a small dose of octreotide. We therefore i nvestigated the preoperative effects of small doses of octreotide (120 -240 mu g/day) administered continuously (with a subcutaneous infusion pump) over a short period (2 or 4 weeks) in nine untreated acromegali c patients. Octreotide therapy resulted in suppression of serum GH and IGF-1 concentrations in 8 out of 9 patients and reduction in pituitar y tumor size measured by MRI in all patients (by 7.9 to 38.5%). In par ticular, considerable reduction in tumor size (more than 20%) occurred in 6 of 9 patients. In three patients assessed serially throughout th e preoperative period, reduction in tumor size was noted within only o ne week after the start of octreotide therapy and reduction rate more than 20% was obtained within the first two weeks. In one patient, supr asellar tumor expansion totally disappeared after such therapy. Our re sults indicate that short-term continuous subcutaneous infusion of a s mall dose of octreotide results in not only inhibition of GH hypersecr etion but also shrinkage of tumor size prior to surgery.