Predictors of surgical outcome and early criteria of remission in acromegaly

Background Transsphenoidal surgery (TSS) is the cornerstone of acromegaly treatment, however there are no robust predictors of surgical outcome and remission can only be defined three months after surgery. Purpose To analyze if biochemical, demographical, radiological, and immunohistochemical characteristics are predictors of surgical remission and investigate if immediate postoperative GH and IGF-I levels can help defining remission earlier. Methods Consecutive acromegaly patients submitted to TSS between 2013-2016 were evaluated. Remission criteria was defined as normal IGF-I and GH <1 mcg/L three months after surgery. Data of age, sex, GH and IGF-I levels, tumor volume, cavernous sinus invasion, T2-weighted signal, Ki-67, and granulation pattern were correlated with remission status. GH and IGF-I levels at 24, 48 h, and one week postoperative were evaluated as early criteria of remission. Results Sixty-nine patients were included (84% macroadenomas) and surgical remission was achieved in 45%. No difference between cured and not cured patients concerning age, gender, preoperative GH or IGF-I levels, tumor volume, T2-weighted signal, Ki-67 and tumor granularity was observed. Remission was obtained in 20 of 36 (56%) of the non-invasive tumors, and in 3 of 16 (19%) of the invasive tumors ( p = 0.017). A GH <1.57 mcg/L 48 h after surgery was able to predict remission with 93% sensitivity and 86% specificity and an IGF-I < 231% ULNR one week after surgery predicted remission with 86% sensitivity and 93% specificity. Conclusion Cavernous sinus invasion is the only preoperative predictor of surgical remission. GH at 48 h and IGF-I one week after surgery can define earlier not cured patients.