OUTCOME OF TRANSSPHENOIDAL SURGERY FOR ACROMEGALY USING STRICT CRITERIA FOR SURGICAL CURE

OBJECTIVE Previous studies of surgical treatment for acromegaly have u sed varied criteria for 'cure', but elevated GH levels are considered to be associated with continuing disease activity. We wished to analys e the results of transsphenoidal pituitary surgery for acromegaly and assess the longer-term outcome for patients not offered further treatm ent when post-operative levels of GH < 5 mU/l were achieved. DESIGN We studied a retrospective group of patients who underwent transsphenoid al surgery for acromegaly at St Bartholomew's Hospital between 1985 an d 1993.PATIENTS One hundred consecutive patients (53 male, mean age 46 years, range 18-68 years) undergoing transsphenoidal surgery for acro megaly were assessed. The patients were followed for a mean of 3.8 yea rs (range 0.5-8 years) after operation. MEASUREMENTS GH levels are rep resented as a mean value from a four-point day curve taken at 0830, 13 00, 1700 and 1900h. ACTH reserve was assessed basally and, if this was normal, with the insulin tolerance or glucagon tests. TSH, T4, PRL, L H, FSH, testosterone or oestradiol and plasma and urine osmolality wer e also measured. RESULTS Post-operatively, 42% of patients achieved a mean GH level of < 5 mU/l. The success of surgery was related to the p reoperative GH level; 65% of the patients with preoperative GH levels < 20 mU/l but only 18% of the patients with GH levels > 100 mU/l achie ved postoperative GH values < 5 mU/l. In addition, tumour size influen ced the outcome of surgery with 61% of patients with a microadenoma bu t only 23% of patients with a macroadenoma achieving post-operative GH levels < 5 mU/l. Of the 42 patients considered in remission postopera tively (mean GH < 5 mU/l), 32 were available for long-term follow-up a nd were not offered any further treatment: only one of these has shown evidence of mild biochemical recurrence after a mean follow-up of 3.8 years (range 0.5-8). There were no peri-operative deaths. Two patient s required surgical repair for CSF leaks and there were eight document ed cases of meningitis. Permanent diabetes insipidus was noted in eigh t patients post-operatively. New anterior pituitary deficiency occurre d in 21% of patients following surgery; 73% had unaltered pituitary fu nction and in 6% recovery of partial hypopituitarism was noted. CONCLU SIONS The stated outcome of surgery depends on the criteria adopted. S afe GH levels (mean levels < 5 mU/l) can be achieved in 42% of an unse lected series of patients with acromegaly and if the tumour is a micro adenoma this figure rises to 61%. Based on the current evidence it is safe not to offer further treatment to those patients in whom post-ope rative GH < 5 mU/l are achieved.