Background: The majority of patients with acromegaly have large tumours and the outcome of conventional management remains poor. Objective: To investigate the clinical application of octreotide-LAR as primary treatment in newly diagnosed patients with GH-secreting pituitary tumours. Design: Open, prospective, multicentre, 24-week follow-up study. Patients: Thirty-four patients were enrolled (20 men, 14 women; mean age, 50 years); 13 had microadenoma [median tumour volume 327 mm3 (range 31-629 mm 3)], 21 had macroadenoma [median tumour volume 1325 mm3 (range 503-11583 mm3)]. Interventions: Octreotide-LAR at the dosage of 20 mg every 28 days for the first 12 weeks increased to 30 mg every 28 days to control GH and/or IGF-I excess in 20 patients (64.7%). Main outcome measures: Primary endpoints were control of GH (fasting <2.5 μg/l) and IGF-I secretion (gender- and age-normalized) and presence and entity of tumour mass shrinkage. Secondary endpoint was improvement of symptoms score. Results: In patients with micro- and macroadenomas GH levels decreased to <2.5 μg/l in 84.6% and 45%, serum IGF-I levels normalized for age and gender in 61.5% and 35% of cases. Failure in achieving either GH <2.5 μg/l or normal IGF-I levels was found in none of the patients with micro- and in 45% of patients with macroadenoma. Median tumour volume was reduced by 54% (range: -90% to +350%) in micro- and by 49% (range -94% to -14%) in macroadenomas. Headache, perspiration and osteo-arthralgias disappeared in 21%, paresthesias in 38%, fatigue in 26% and carpal tunnel syndrome in 15%. The treatment was well tolerated: more frequent adverse events were gastrointestinal (in 44%). Conclusions: In both patients with micro- or macroadenoma, primary octreotide-LAR treatment controls hormone excess, induces tumour shrinkage and improves symptoms of acromegaly with limited side effects and can be therefore successfully employed in patients with contraindications for surgery or in those who refuse surgery.
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