Outcomes of Gamma Knife surgery for craniopharyngiomas

Gamma Knife surgery (GKS) has emerged as a valuable adjuvant treatment modality for recurrent or residual craniopharyngioma. However, prognostic factors pertaining to progression-free survival (PFS) remain poorly understood. A study was conducted to address this issue. A total of 37 consecutive patients undergoing 39 sessions of GKS procedures targeting the solid portions of the tumors at our institution between 1989 and 2005 were analyzed. Twenty-one male and 16 female patients comprised this study. Median age at GKS was 36 years (range, 4-78). Median tumor volume was 1.6 cm(3) (range, 0.1-18.6), median marginal dose was 14.5 Gy (range, 6-25), and median maximal dose was 30 Gy (range, 15.6-60). Median follow-up was 50 months (range, 8-212). Univariate and multivariate analyses using Cox proportional hazards model were employed to identify the potential prognostic factors including tumor volume, marginal dose, gender, age at GKS, and status of visual field defect (VFD) in terms of in-field PFS. The actuarial 3- and 5-year in-field PFS were 84.8 and 67.0%, respectively. On univariate analysis, absence of VFD at GKS was a favorable prognostic factor (hazard ratio: 0.279; 95% CI, 0.085-0.913, P = 0.035), whereas on multivariate analysis, absence of VFD at GKS, tumor volume ≤1.6 cm(3), and marginal dose >14.5 Gy related to a longer in-field PFS. GKS may offer reasonable control of recurrent or residual craniopharyngiomas. There was a consistent correlation between absence of VFD at the time of GKS and in-field PFS.