A PROSPECTIVE MULTICENTER TRIAL OF OCTREOTIDE IN 24 PATIENTS WITH VISUAL DEFECTS CAUSED BY NONFUNCTIONING AND GONADOTROPIN-SECRETING PITUITARY-ADENOMAS

OBJECTIVE: The somatostatin analog octreotide has been demonstrated to improve optic tract compression caused by pituitary macroadenomas wit hin hours of ifs administration and/or reduce tumor size in some patie nts. We report the results of a prospective multicenter study of the e ffects of octreotide on visual function and tumor size in patients wit h nonfunctioning pituitary adenomas or gonadotropin-secreting adenomas . METHODS: Twenty-four patients with visual defects caused by histolog ically confirmed macroadenomas were administered octreotide via contin uous subcutaneous infusion, as follows: 100 mu g the Ist day and, if n ecessary, 200 mu g the 2nd and then 100 or 200 mu g three times daily if visual function improved. Vision was assessed after 4 days, 1 month , and 2 months, including tumor size evaluation. Visual improvement wa s defined by a net gain of at least 2/10 in acuity and/or of more than 20% of the surface of one isopter (a reduction in tumor volume of gre ater than or equal to 20% of the initial measurement); opposite change s were defined as deterioration. RESULTS: Visual improvement was noted in 13 of 24 patients, 10 of 23 patients and 9 of 22 patients, and was not noted in 11 of 24 patients, 14 of 23 patients, and 13 of 22 patie nts after 4 days, 1 month, and 2 months, respectively. After 2 months, three adenomas had shrunk, three had not changed in size, and one had increased; visual function improved in the seven patients with these adenomas, Octreotide was discontinued in 13 patients for lack of effic acy. CONCLUSION: The incidence of visual improvement and tumor shrinka ge noted in this study was higher than previously reported. Our data s uggest that early onset of visual improvement might help in deciding w hich patients profit from octreotide. However, concomitant gain in vis ual acuity with deterioration in visual fields or visual improvement w ith an increase (moderate) in tumor size can occur.