Endocrine Abstracts

Objective: Transphenoidal hypophysectomy is currently the primary treatment for patients with acromegaly. Advances in medical and radiotherapy treatment options have resulted in uncertainty whether surgery should remain the treatment of choice for all acromegalics. The surgical cure rate for acromegaly is variable and there is a need to accurately counsel patients regarding the likelihood of successful surgical cure. We examined how lateral tumour extension into the cavernous sinus affected surgical cure rate in our patients.

Method: We performed a retrospective study of acromegalic patients who underwent transphenoidal hypophysectomy by a single neurosurgeon. Radiologists were blinded to outcome and graded pre-operative MRI scans on the basis of lateral and suprasellar tumour extension. Cure was defined as a post-operative mean growth hormone (GH) level of <5 mu/l or a nadir GH of <2 mu/l on an oral glucose tolerance test (GTT). We predicted that patients with lateral tumour extension would not be surgically cured.

Result: We have now studied 28 cases. Failed surgical cure was accurately predicted in 14 of 19 (74%) cases with lateral tumour extension. Eight of nine cases (89%) with no lateral extension were cured. Predicting failure on the basis of lateral tumour extension had a positive predictive value of 74%, negative predictive value of 89% sensivity of 93% and specificity of 62%. There was no difference in pre-operative GH levels (random GH or basal GH on a GTT) between patients with and without lateral tumour extension (mean GH =46.2 vs 45.1 mu/l, P=0.96). Interestingly, lateral extension was associated with an elevated prolactin of >600 miU/l (70 vs 17% with no lateral tumour extension).

Conclusion: Our data suggests lateral tumour extension into the cavernous sinus predicts a surgical cure rate of 26%. Absence of lateral tumour extension is highly predictive of surgical success.