Gamma knife radiosurgery for brainstem metastases

Takuya Kawabe1, Masaaki Yamamoto2, Bierta E Barfod3, Yoihi Urakawa3

1Hitachi-Naka, Japan 2Ibaraki, Japan 3Katsuta Hospital Mito Gamma House, Hitachi-naka, Japan

Keywords: brain stem, gamma knife, brain metastasis, outcome, radiosurgery

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     The efficacy of gamma knife radiosurgery (GKRS) for brainstem metastases (METs) is not yet fully understood. 
     We retrospectively studied our database of patients with GKRS-treated brainstem METs.
     200 patients were studied over a 13 year period.
     In total, 200 patients (79 women, 121 men, mean age; 64 range; 36-86 years) who underwent GKRS at our facility between July 1998 and April 2011 were analyzed. The most common primary site was the lung (136 patients) followed by the gastrointestinal tract (24), breast (18), kidney (12) and others (10). Among a total of 222 tumors, lesion location was the pons in 120, the midbrain in 66 and the medulla oblongata in 36. The mean and median tumor volumes were 1.3 and 0.2 (range; 0.005-10.7) cc, the median peripheral dose 18.0 (range; 12.0-25.0) Gy.
     The overall median survival time (MST) was 6.0 months. MSTs according to Recursive Partitioning Analysis (RPA) were 9.4 months in Class 1 (20 patients), 6.0 in Class 2 (171) and 1.9 in Class 3 (nine). Better KPS and single metastasis were significant factors favoring survival. Neurological and qualitative survival rates were 95.0% and 88.0% at the 6th post-GKRS month and 91.4% and 84.3% at the 12th post-GKRS month, respectively. Follow-up imaging studies were available for 129 patients (65%). The tumor control rate was 91.1 % at the 6th post-GKRS month, 64.3% at the 12th post-GKRS month.
     This was a retrospective study.
     Our present results suggest GKRS to be effective for brainstem METs.


Project Roles:

T. Kawabe (), M. Yamamoto (), B. Barfod (), Y. Urakawa ()