Evaluation of the role of Gamma Knife surgery in the treatment of craniopharyngiomas.

The management of craniopharyngioma involves balancing adequate reduction in tumor volume and prevention of recurrence while minimizing damage to delicate surrounding structures. Because of the lesion's proximity to the optic chiasm and its relationship to the hypothalamic-pituitary axis, morbidity rates following treatment can be high. Gamma Knife surgery (GKS) is now being considered as a viable method of providing tumor control while ensuring minimal side effects. The authors conducted a literature review of 10 studies in which GKS was used to treat craniopharyngioma; some lesions had been previously treated and some had not. The mean marginal dose ranged from 5 to 16.4 Gy (mean 12.3 Gy). Tumor control was achieved in 75% of cases overall and varied with tumor subtype (cystic, solid, mixed). Control was seen in 90% of solid, 80% of cystic, and 59% of mixed tumors. The overall morbidity rate resulting from radiosurgery was 4% and the overall mortality rate was 0.5%. These results suggest that GKS may provide a favorable benefit-to-risk profile for many patients with craniopharyngiomas.