Low Dose Regimens of Hypofractionated Stereotactic Radiosurgery Therapy to Cavernous Sinus Meningiomas Does Not Cause Subsequent Pituitary Hormone Deficits

Presentation Number: OR21-3
Date of Presentation: April 2nd, 2017

Kevin C.J. Yuen*, Annelise Long, Alissya S.M. Yuen, Zachary N. Litvack and Sandra S. Vermeulen
Swedish Neuroscience Institute, Seattle, WA

Abstract

Background: Microsurgery for cavernous sinus meningiomas (CSMs) has its limitations due to its close proximity to cranial nerves II to VI and to the internal carotid artery, with high rates of subsequent tumor recurrences, and cranial nerve and vascular morbidity. Therefore, application of stereotactic radiosurgery (SRS) to CSM has been proposed as the primary treatment modality for such tumors, especially those that are not significantly compromising the optic pathway. However, although the control rates for SRS therapy has been reported to be excellent, the effects on causing subsequent pituitary hormone deficits (PHDs) using low hypofractionated dosing regimens have not been well-studied.

Aims: Since the SRS dose required to control meningiomas are typically less than those used to treat non-functioning pituitary adenomas, the aim of this study was to ascertain whether low dose regimens of hypofractionated SRS therapy to CSMs can cause subsequent PHDs.

Methods: A retrospective chart review from May 2013 to May 2015 of patients with CSM with no previous surgery that underwent SRS therapy for tumor control. Pre- and post-neuroendocrine function were assessed and correlated to the full and partial hypo-fractionated dose that the pituitary gland received.

Results: Five patients with confined CSM [2 males/3 females, median age 62.0 (range 36-62) yr and BMI 24.6 (range 22.2-34.0) kg/m2] received 5 fractions of SRS therapy [median radiation dose 27.5 (range 22.0-236.0) Gy and median isodose treatment line 69.0 (range 65.0-80.0)%], whereas the pituitary gland received a mean radiation dose of 12.1 (mean minimum dose 5.4 and mean maximum dose 20.2) Gy/fraction. Before SRS therapy, Patient 1 had TSH and gonadal deficiency, Patient 2 had TSH and GH deficiency, Patient 4 had gonadal deficiency, and Patients 3 and 5 had no PHD. After a follow up period ranging from 6 to 30 [mean (SE) 12.2 (4.5)] months, none of the patients developed subsequent biochemical evidence of PHDs, and neither did any of the patients report of neurological deterioration of pre-existing or to the onset of new symptoms.  

Discussion: Low dose regimens of hypofractionated SRS therapy is an effective treatment modality of CSM, and does not appear to cause subsequent PHDs. Larger and longer-term prospective studies are needed to substantiate these findings and to ascertain the lowest dose of hypofractionated SRS therapy that can cause PHDs, so that a ‘safe’ threshold dose can be determined.

 

Nothing to Disclose: KCJY, AL, ASMY, ZNL, SSV