Hypopituitarism after gamma knife radiosurgery for pituitary adenomas: long-term results from a single-center experience

Objective The aim of this study was to investigate the incidence and risk factors of new-onset hypopituitarism after gamma knife radiosurgery (GKRS) for pituitary adenomas in a single center. Methods In this retrospective study, 241 pituitary adenoma patients who underwent GKRS from 1993 to 2016 were enrolled. These patients had complete endocrine, imaging, and clinical data before and after GKRS. The median follow-up time was 56.0 (range, 12.7-297.6) months. Results Fifty patients (20.7%) developed new-onset hypopituitarism after GKRS, including hypogonadism (n = 22), hypothyroidism (n = 29), hypocortisolism (n = 20), and growth hormone deficiency (n = 4). The median time to new-onset hypopituitarism was 44.1 (range, 13.5-141.4) months. The rates of new-onset hypopituitarism were 7%, 16%, 20%, 39%, and 45% at 1, 3, 5, 10, and 15 years, respectively. For those patients treated with a single GKRS, sex (p = 0.012), suprasellar extension (p = 0.048), tumor volume (>= 5 cm(3)) (p < 0.001), tumor progression (p = 0.001), pre-existing hypopituitarism (p = 0.011), and previous surgery (p = 0.009) were significantly associated with new-onset hypopituitarism in univariate analysis. In the multivariate analysis, tumor volume (>= 5 cm(3)) and tumor progression were associated with new-onset hypopituitarism (hazard ratio [HR] = 3.401, 95% confidence interval [CI] = 1.708-6.773, p < 0.001 and HR = 3.594, 95% CI = 1.032-12.516, p = 0.045, respectively). For patients who received 2 or more times GKRS, no risk factors associated with new-onset hypopituitarism were found. Conclusion New-onset hypopituitarism was not uncommon after GKRS for pituitary adenomas. In this study, large tumor volume (>= 5 cm(3)) and tumor progression were associated with new-onset hypopituitarism after a single GKRS.