The outcome of surgery for acromegaly: the need for a specialist pituitary surgeon for all types of growth hormone (GH) secreting adenoma.

OBJECTIVE

Acromegaly is associated with reduced life expectancy, while therapeutic 'cure' (defined by achievement of GH levels < 5 mU/l) is associated with normalization of life expectancy. Surgery remains the treatment of choice but in those in whom operative 'cure' is not achieved, radiotherapy and/or medical treatment are valuable treatment modalities. The chance of subsequent 'cure' with radiotherapy or somatostatin analogue therapy is increased if the post-operative GH level is reduced below 30 mU/l. Using strict criteria for cure and a single dedicated pituitary surgeon, two large European studies reported 'cure' rates of 42% and 56%. In the Manchester region, surgery for these patients has been performed by a number of neurosurgeons, with no specific designated pituitary surgeon dominating the picture. We wished to examine the impact of this surgical strategy on cure rates and the incidence of a post-operative GH level below 30 mU/l.

DESIGN

We reviewed the GH results between 1974 and 1997 for every acromegalic who had been referred to the endocrine departments of the two Manchester hospitals responsible for the majority of pituitary disease referrals in Manchester and who had been subsequently referred for pituitary surgery.

PATIENTS AND MEASUREMENTS

Seventy-three (33 male) patients had had GH status assessed before and after surgery by an OGTT or GH profile. The patients were aged between 19 and 70 (mean 43) years at surgery. Seventy-one underwent transsphenoidal and 2 transfrontal surgery. Nine surgeons performed operations.

RESULTS

Eighteen (24.7%) had microadenomas and 51 (69.9%) macroadenomas. In 4 patients (5.5%) insufficient data were available to size the adenoma. 17.8% of patients were cured by surgery, 38.8% with microadenomas and 11.8% with macroadenomas. In addition, of 52 patients whose GH levels were > 30 mU/l before surgery, only 27 (51.9%) had GH levels below 30 mU/l post-operatively (81.8% of microadenomas, 43.2% of macroadenomas).

CONCLUSION

In comparison with other series, the cure rate in this study is significantly lower. The success in reducing GH levels below 30 mU/l post-operatively is difficult to compare with previously published studies, as few groups have analysed their data in this manner. Nonetheless, of our acromegalic patients with a pretreatment GH level in excess of 30 mU/l, nearly 50% have similar GH status postoperatively, thereby rendering them less amenable to cure by alternative therapeutic modalities. This highlights the importance of a specialist pituitary surgeon, not only for GH secreting microadenomas but also for GH secreting macroadenomas. If these patients are not 'cured', the cost of continuing therapy becomes a significant burden on health-care costs. In addition, if the postoperative GH levels remain above 30 mU/l the chances of achieving adequate control of GH levels are greatly reduced, thereby increasing mortality rates as well as morbidity in these patients.