SIGNIFICANT ELEVATION OF GROWTH HORMONE LEVEL IMPACTS SURGICAL OUTCOMES IN ACROMEGALY

Objective: Transsphenoidal adenomectomy (TSA) is first-line treatment for acromegaly. Our aim was to determine the impact of pre-operative biochemical parameters on the outcomes of surgery. Methods: Retrospective case series of 79 consecutive acromegalics operated between 1994 and 2013. Inclusion criteria were: first TSA, pathology-confirmed growth hormone (GH) adenoma, and follow-up >3 months. Biochemical remission was defined as normal insulin-like growth factor 1 (IGF-1) without adjuvant therapy during follow-up. Results: Median follow-up was 35.4 months (range, 3 to 187 months). Logistic regression analysis showed that the best model to predict long-term remission included the following pre-operative markers: GH, tumor diameter, and cavernous sinus invasion (CSI) (area under the curve, 0.933). A threshold GH of 40 ng/mL was associated with long-term remission (sensitivity, 97%; specificity, 42%). Group A (GH >40 ng/mL) comprised 19 patients (9 men); age, 43 +/- 13 years; tumor diameter, 2.7 +/- 1.0 cm; 73.7% with CSI; and pre-operative median GH, 77.8 ng/mL (interquartile range [IQR], 66.7 to 107.0 ng/mL). Three patients (15%) in group A achieved remission at 3 months, but 2 patients recurred during follow-up. Group B ( GH <= 40 ng/mL) comprised 60 patients (25 men); age, 47 +/- 13 years; tumor diameter, 1.6 +/- 1.0 cm; 35% with CSI, pre-operative median GH, 6.9 ng/mL (IQR, 3.4 to 16.9 ng/mL). Thirty-five patients (58%) in group B achieved remission at 3 months without recurrence during follow-up. Group A had larger tumors and a higher proportion of tumors with CSI (P<.05). Conclusion: Both GH and IGF-1 should be measured pre-operatively, as highly elevated GH levels negatively impact long-term surgical remission. This strategy allows early identification of patients who require adjuvant therapy and may decrease time to biochemical control.