THE OUTCOME OF HYPOPHYSECTOMY FOR PROLACTINOMAS IN THE ERA OF DOPAMINE AGONIST THERAPY

OBJECTIVE Dopamine agonists are the primary therapeutic modality for t he majority of patients with prolactinomas, with pituitary surgery res erved for those patients intolerant of or resistant to these agents. M ost published surgical series, however, contain patients treated by su rgery as the primary therapeutic modality. Previous exposure to dopami ne agonists or the selection of patients with prolactinomas resistant to conventional therapy may potentially compromise the surgical succes s rate. The purpose of this study was to evaluate the efficacy and saf ety of pituitary surgery for prolactinomas in a tertiary referral cent re where the majority of patients were operated on after treatment wit h dopamine agonists. DESIGN A retrospective review of the outcome of p ituitary surgery for prolactinomas performed at a tertiary neurosurgic al centre by a single neurosurgeon. PATIENTS Twenty-three patients und erwent excision of a macro and 11 excision of a micro-prolactinoma. ME ASUREMENTS Pituitary tumour diameter was determined by CT or MRI imagi ng. Pre and post-operative measurements were made of serum PRL concent ration (off dopamine agonist therapy), free T4, free T3, LH and testos terone (males). Post-operative restoration of a menstrual cycle was ta ken to indicate resolution of hypogonadism in female patients. RESULTS The majority (73 . 9%) of the patients with macro and all with micro- prolactinomas had received dopamine agonists preoperatively. Of the 23 patients with macroprolactinomas, in whom the median preoperative PRL concentration was 13255 mU/l, 17 (73 . 9%) had radiological evidence of suprasellar extension and 5 (21 . 7%) cavernous sinus invasion. Onl y 4 (17 . 4%) of the patients with macroprolactinomas had a normal ser um PRL post-operatively, although there was an improvement in visual f ields in 66% of those with preoperative defects. The median preoperati ve PRL concentration was 4309 mU/l in the patients with microprolactin omas, significantly lower than in the macroprolactinoma group (P = 0 . 02). Despite a significant fall in serum PRL postoperatively (median PRL 860 mU/l, P = 0 . 0001), only 45 . 5% of patients had a normal ser um PRL concentration after surgery. CONCLUSIONS The cure rate followin g pituitary surgery for prolactinomas in a tertiary referral centre wa s low when compared with previous series in which surgery was used as the primary therapeutic modality. We suggest this may result both from dopamine agonist pretreatment and the referral of prolactinomas resis tant to conventional therapy. The outcome is probably a more realistic reflection of the results of pituitary surgery for prolactinomas as c urrently practised in the majority of neuroendocrine centres.