Effects of Initial Therapy for Five Years with Somatostatin Analogs for Acromegaly on Growth Hormone and Insulin-Like Growth Factor-I Levels, Tumor Shrinkage, and Cardiovascular Disease: A Prospective Study

Objective: The objective of the study was to evaluate the efficacy of 5 yr of depot somatostatin analogs (SSAs) as first-line therapy in acromegaly. Outcome Measures: Primary measures were fasting GH 2.5 mu g/liter or less and IGF-I normalized for age and tumor shrinkage. Secondary measures were control of hypertension, arrhythmias, left ventricular hypertrophy, diastolic and systolic dysfunction, and change in lipid and glucose profile. Patients: Patients included 45 de novo patients (18 women and 27 men, aged 20-82 yr); 28 were treated with octreotide-long-acting release and 17 with lanreotide. Results: GH was controlled in 100% and IGF-I levels in 97.8%, tumor shrinkage was 74.9 +/- 22.1 and 78.2 +/- 14.5%, in the octreotide-long-acting release and lanreotide groups, respectively. There was a significant improvement in the prevalence of hypertension (from 46.7 to 22.2%, P = 0.027), arrhythmias (from 17.8% to zero, P = 0.01), left ventricular hypertrophy (from 82.2 to 42.2%, P < 0.0001), diastolic dysfunction (from 60.0 to 15.6%, P < 0.0001), systolic dysfunction (from 40.0 to 4.4%, P < 0.0001), and hypertriglyceridemia (from 40.0 to 4.4%, P < 0.0001). The prevalence of impaired glucose tolerance (IGT; from 28.9 to 20.0%. P = 0.46) and diabetes mellitus (from 22.4 to 31.1%, P = 0.64) did not change. Conclusions: In patients with severe comorbidities and those who refuse surgery, 5 yr of exclusive SSA therapy induce successful control of GH and IGF-I; tumor shrinkage (by median 80%), and improvement of hypertension, cardiac performance; and dyslipidemia. No patient was withdrawn from treatment because of side effects, and glucose tolerance was stable. We suggest that first-line SSA treatment may be safely continued in patients with acromegaly, according to an individual patient's indications and preferences. (J Clin Endocrinol Metab 94: 3746-3756, 2009)