Optimal strategy of gamma knife radiosurgery for craniopharyngiomas
To analyze the outcomes of gamma knife radiosurgery (GKS) for craniopharyngiomas and elucidate the optimal strategy.
Between 1998 and 2016, 35 patients underwent GKS for the treatment of 40 recurrent or residual craniopharyngiomas. Among 40 GKSs, 22 procedures were single-session GKSs and 18 procedures were fractionated GKSs. In cases of single-session GKS, the median marginal dose was 15 Gy (range 10–20 Gy). In cases of fractionated GKS, the median marginal dose was 6 Gy (range 5–7.5 Gy) of three fractions. The radiation dose was calculated to the biologic equivalent dose (BED) using α/β ratios of 10 and 2.
The location of the tumor, the distance between the optic nerve and tumor (> 10 mm), BED 10 (> 35 Gy), and BED2 (> 80 Gy) were statistically significant with overall response rate (P = 0.008, 0.02, 0.03, and 0.002, respectively). There was a statistically significant difference in progression-free survival according to the distance between the optic nerve and tumor (> 10 mm) and the location of tumor (P = 0.03 and 0.03, respectively). Multivariate logistic regression analysis showed the hypothalamus group had an odds ratio of 0.04 compared with the suprasellar group for tumor progression. The group with BED2 > 80 Gy had an odds ratio of 0.049 compared with the group with BED2 < 80 Gy.
A sufficient dose is required for treating craniopharyngiomas using single-session and fractionated GKS. The outcomes of GKS can be predicted according to the location of tumor, the distance between the optic nerve and tumor and BED value.
KeywordsStereotactic radiosurgery Gamma knife radiosurgery Craniopharyngiomas Fractionation Biologic equivalent dose Location of tumor
This study is supported by the by a Grant (No.: HI16C-1111-020016 to Kim YH) from the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea and a Grant (No.: NRF-2017R1A2B2008412 to Kim YH) from National Research Foundation of Korea by the Ministry of Science, ICT and Future Planning (MSIP) of Korea.
Compliance with ethical standards
Conflict of interest
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
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