Treatment of acromegaly with octreotide-LAR: extensive experience in a Brazilian institution

Abstract

Objective: Somatostatin analogues have become the mainstay of the medical treatment of acromegaly. The aim of our study was to evaluate the efficacy and tolerability of octreotide-LAR (OCT-LAR) treatment in acromegalic patients.

Design: Prospective open trial.

Patients and methods: Eighty acromegalic patients (46 women; 18-80 years) were treated with OCT-LAR. Mean +/- SD duration of follow-up was 16.6 +/- 6.6 months (6-24 months). Twenty-eight patients received OCT-LAR as primary treatment. The target was to achieve normal IGF-I levels. Clinical activity was evaluated by symptom score and fasting samples for GH and IGF-I serum concentrations, obtained under basal conditions as well as during treatment. Pituitary tumour volume was assessed by magnetic resonance imaging of the sella. A tumour volume reduction of at least 25% was considered significant.

Results: Clinical improvement was attained in most patients. Fifty-nine (74%) of them attained mean GH < 2.5 ng/ml and 33 (41%) achieved normal IGF-I by the 24th month of treatment. GH and IGF-I control increased throughout treatment. Regarding the 46 patients treated for at least 12 months there was a significant decrease of GH and IGF-I levels by the third month compared to basal levels, persisting with no subsequently variation. In the patient group that achieved normal serum IGF-1 during treatment (controlled group: n = 43) 20 patients maintained normal levels up to the latest follow-up, whereas 23 of them once again showed altered serum IGF-1-values of some measurements during follow-up, despite dose maintenance or elevation. Baseline percentage of the upper limit of IGF-I normal range, GH levels by the third month and length of treatment were predictive factors of IGF-I normalization. Tumour shrinkage occurred in 76% of primary patients. Among 21 diabetic patients, four worsened and five improved glycaemic control, based on glycated haemoglobin. One previously intolerant patient progressed to overt diabetes. Nine patients developed gall bladder sludge, other nine patients acquired microlithiasis and one patient developed gallstone pancreatitis.

Conclusion: OCT-LAR is an effective agent in alleviating symptoms, suppressing GH, normalizing IGF-I and inducing tumour shrinkage in many acromegalic patients. Overall, OCT-LAR is well tolerated and should be recommended for nonsurgically cured acromegalics, and also be considered as primary therapy for selected cases, mainly for those with a low probability of surgical cure.