Surgical Results and Predictors of Initial and Delayed Remission for Growth Hormone-Secreting Pituitary Adenomas Using the 2010 Consensus Criteria in 162 Patients from a Single Center.

BACKGROUND: The factors associated with initial and delayed remission after growth hormone (GH)-secreting pituitary adenoma excision have not been completely elucidated.

METHODS: We recruited 185 consecutive patients who had undergone resection of GH-secreting pituitary adenomas from January 2013 to December 2014 and assessed their tumor characteristics and surgical outcomes. The criteria for initial or delayed remission (using the 2010 consensus criteria) were normalized insulin-like growth factor 1 (IGF-1) levels, GH levels <0.4 μg/L with an oral glucose tolerance test, and/or random GH levels <1.0 μg/L at or after the postoperative 3-month (PO3M) follow-up, without adjuvant therapy.

RESULTS: Remission was achieved in 92 of 162 patients (56.8%) after surgery alone and was associated with a lower Knosp grade of 0-2 and lower postoperative day 1 GH level on multivariate regression analysis. A baseline IGF-1 index (IGF-1 level/upper limit of normal) of <2.835 predicted for initial remission at the PO3M follow-up (positive predictive value, 95.3%; negative predictive value, 36.6%; P < 0.001). The PO3M IGF-1 index was significantly lower in the delayed remission group than in the nonremission group. Furthermore, the former had had fewer invasive tumors (1.23 ± 0.21 vs. 1.77 ± 0.37 [9.52% vs. 76.47%]; P < 0.001). A PO3M IGF-1 index of <1.485 predicted for delayed remission during subsequent follow-up (positive predictive value, 84.6%; negative predictive value, 92.3%; P < 0.001).

CONCLUSIONS: A lower Knosp grade of 0-2 and lower postoperative day 1 GH level were independent predictors of surgical remission. The baseline IGF-1 and PO3M IGF-1 indexes might predict for initial and delayed remission, respectively.