Background: Acromegaly is characterised by excess growth hormone secretion and is associated with increased morbidity and mortality. Current guidelines define cure or control as normal IGF-1 and random growth hormone concentrations <1microg/L (1).
Objective: To audit the immediate and long-term outcomes of patients treated surgically for acromegaly at Christchurch Hospital, New Zealand, a small tertiary referral centre with a single pituitary neurosurgeon.
Methods: We undertook a retrospective case review of all cases of acromegaly treated via endoscopic transnasal transphenoidal surgery between May 2000 and August 2013. Biochemical and clinical data concerning pre-operative findings, post-surgical outcome and long-term follow-up was collected.
Results: 40 patients (15 male, 25 female) were identified. 12 tumours were microadenomas, and 28 macroadenomas. All patients had at least one measurement of random GH and IGF-1 within 6 months of surgery (mean 44 days, range 2-105). 50% (6/12) of microadenomas met cure criteria compared with 35% of macroadenomas (10/28). Three patients with invasive tumours underwent stereotactic radiotherapy and 8 patients commenced medical therapy within 6 months of surgery.
Average follow-up was 70.1 months for 36/40 patients. 41% of patients were on medical therapy (octreotide, cabergoline or in combination), 50% of macroadenomas, 30% of microadenomas. 64% of patients had both IGF-1 and GH within target range; 54% of macroadenomas and 83% of microadenomas. 3 macroadenomas were controlled with cabergoline alone. 33/36 tumours had normal IGF-1. Mean random GH concentrations for macroadenomas was 0.90ug/L, for invasive tumours 1.66ug/L, and 0.58ug/L for microadenomas.
Conclusions: Surgical cure rates for microadenoma are lower than reported elsewhere in the literature but may not reflect true growth hormone status as many patients were assessed less than 3 months following surgery. Consistent measurement of growth parameters at least 3-6 months after surgery is recommended. Most patients achieved good biochemical control at long term follow-up although many require ongoing medical therapy. Cabergoline is an effective therapy even in patients with macroadenoma.