Outcome of partially irradiated recurrent nonfunctioning pituitary macroadenoma by gamma knife radiosurgery
Gamma knife treatment outcome of large pituitary tumors which are only partially irradiated secondary to immediate proximity to critical structures such as the optic apparatus have not been rigorously studied.
Materials and methods
From July 2003 to December 2013, there were 41 cases of recurrent or residual nonfunctioning pituitary macroadenoma partially treated with gamma knife radiosurgery (GKRS) because the adenoma obscured part of the optic apparatus on planning SRS MR imaging.
The follow up period after GKRS was 92.3 ± 5.6 months. The percentage of tumor coverage with the full dose was 88.5 ± 0.7%. Five of 43 (11.6%) patients experienced a transient visional decrease and one patient experienced a permanent visual field defect. During the follow up, two patients underwent transphenoidal surgery and one patient had a craniotomy due to tumor progression. Seven patients (16.2%) developed cortisol and thyroxine deficiencies. In multiple variant analyses, transient visual decline was correlated to the tumor volume (> 3.5 cc), percentage of tumor coverage (< 90%), the distance from the optic apparatus to the pituitary stalk (> 15 mm) and percentage of tumor above the orbital apex (65%).
In the limited case of this cohort, we found that partially treated pituitary nonfunctioning macroadenoma yielded a high tumor control rate. However, visual decline as a result of tumor progression or radiation effect can occur in a minority of patients. The radiosurgical technique warrants further study to better define the long-term risk to benefit profile for its use in complex pituitary macroadenoma obscuring part of the optic apparatus.
KeywordsPituitary macroadenoma Gamma knife radiosurgery Irradiation optic nerve neuropathy
Gamma knife radiosurgery
Magnetic resonance imaging
Picture archiving and communications system
Time of flight
Insulin-like growth factor 1
The authors would like to thanks all assistant and Biostatistics Task Force of Taichung Veterans General Hospital for their kind assistances in the manuscript preparation and statistical analysis.
SCC and YMC collected the data and wrote the manuscript. SMH, LSD and THK collected the data of imaging and visual field for analysis. CYJ and SML helped in statistical analysis. SJ helped to design this study. PHC conducted the study design and collected the data and edited the manuscript.
The funding (TCVGH-1064903C and TCVGH-PU1068101) was received from Taichung Veterans General Hospital, Taichung, Taiwan.
Compliance with ethical standards
Conflict of interest
There was no conflict of interest.
Approval by ethical committee of Taichung Veterans General Hospital is on record No. CG12718B.