Long-Term Outcomes of Transsphenoidal Surgery for Management of Growth Hormone–Secreting Adenomas: Single-Center Results

Introduction: Transsphenoidal surgery is advocated as the first-line management of growth hormone (GH)-secreting adenomas. While disease control is defined by strict criteria for biochemical remission, the length of follow-up needed is not well defined in literature. In this report, the authors present their long-term remission rate and identify various predictive factors that might influence the clinical outcome.

Materials and Methods: The authors conducted a single-institute retrospective analysis of all transsphenoidal procedures for GH-secreting adenomas from January 2000 to June 2016. The primary outcome was defined as biochemical remission according to the 2010 consensus criteria and measured at the 1-year mark postoperatively as well as on the last recorded follow-up appointment. Secondary variables included recurrence rate, patterns of clinical presentation, and outcome of adjuvant therapy including repeat surgery, and subgroup analysis for patients who have “biochemical or radiological discordance”— patients who achieved biochemical remission but with incongruent IGF1/GH or residual tumor on MRI. Recurrence-free survival analysis was conducted for patients who achieved remission at 1-year postop.

Results: Eighty-one cases (45 females and 36 males) with confirmed acromegaly treated with transsphenoidal surgery were included (62 pure endoscopic cases and 19 microscopic endoscopic-assisted cases). Primary biochemical remission after surgery was achieved in 59 cases (73%) at 1-year mark postoperatively. However, only 41 patients (51%) remained in primary surgical remission (without any adjuvant treatment) at their last follow-up appointment indicating a recurrence rate of 31% (18/59 patients) over the duration of follow-up (average: 100 ± 61 months). Long-term remission rates for pure endoscopic and endoscopic-assisted cases appeared similar (48 vs. 52%, p = 0.6). Similarly, no significant difference in long-term remission was detected between primary surgery and repeat surgery (54 vs. 33%, p = 0.22). Long-term remission was significantly influenced by extent of surgical resection, cavernous sinus invasion (radiologically as well as surgically reported), preoperative IGF-1 levels, and early postoperative GH and IGF-1 levels (within 24–48 hours postoperative) as well as by the clinical grade with lower remission rates in patients with dysmorphic features and/or medical comorbidities (grades 2–3) compared with minimally symptomatic/silent cases (grade 1).

Conclusion: Long-term surgical remission rate appears to be significantly less than “early” remission rates and is highly dependent on the extent of tumor resection. The authors advocate a long-term follow-up regimen and propose a clinical grading system that may aid in predicting long-term outcome in addition to the previously reported anatomical factors. The role of repeat surgery is highlighted.