Gamma Knife Radiosurgery For Treatment Of Residual Non-functioning Pituitary Adenoma In A Large Single Institute Series

Piero Picozzi, MD1, Micol Angela Valle2, Marco Losa2, Alberto Franzin3, Antonella Del Vecchio4, Camillo da Ferrari2, Angelo Bolognesi2, Pietro Mortini2

1Department of Neurosurgery, IRCCS San Raffaele 2Gamma Knife Unit, Dept of Neurosurgery, IRCCS San Raffaele, Milano, Italy 3Mi, Italy 4Milan, Italy

Keywords: pituitary adenoma, cavernous sinus, gamma knife, outcome, hormone dysfunction

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     The aim of this study is to evaluate efficacy and safety of Gamma Knife radiosurgery (GKRS) for treatment of incompletely removed non-functioning pituitary adenoma (NFPA).
     Between 1994 and 2008, 166 patients (82 men and 84 women) with a diagnosis of NFPA who had previously undergone surgical treatment at our center underwent GKRS for residual pituitary tumor. 108 patients had undergone surgery once; 49 patients twice and the remaining 9 patients, three times. No patient had previously received external fractionated radiotherapy.
     Medial marginal dose was 15 Gy with isodose at 50%; median dose to optic chiasm was 7.4 Gy (IQR 5.1- 9.5 Gy). GKRS was performed in 111cases (67.7 %) to prevent regrowth of residual tumor, while 53 cases (32.3 %) underwent GKRS after the regrowth of residual NFPA. Baselines and follow-up studies included MRI, hormone evaluation and neuro-ophthalmologic examination 6 and 12 moths after GKRS and then at yearly intervals.
      The mean follow-up after GKRS was 43.6±2.9months. 153 patients have had at least 6 months of follow-up after radiosurgery and are included in the following analyses. Volume of treated residual tumor was 2.2±0.2 cm3 (IQR 0.2 – 17.7 cm3). Three patients had severe headache for two months after GKRS. Visual function did not deteriorated in any patients. New cases of hypogonadism, hypothyroidism and hypoadrenalism occurred in 11.4 %, 6.1 % and 3.6% of patients at risk. There were 7 recurrences (4.6%). The 3 years recurrence-free survival was 97.9% (95% CI, 95.1-100) and 5 year recurrence free survival was 94.8% (95% CI, 89.8-99.9).
     This is a retrospective study.
     GKRS was effective in controlling the growth of residual or recurring NFPA after previous maximal surgical debulking.
     Also, GKRS carries a low risk of side effects and hypopituitarism.


Project Roles:

P. Picozzi (), M. Valle (), M. Losa (), A. Franzin (), A. Del Vecchio (), C. da Ferrari (), A. Bolognesi (), P. Mortini ()