Gamma Knife surgery for metastatic brain tumors without prophylactic whole-brain radiotherapy: results in 1000 consecutive cases.

OBJECT: The authors analyzed the effectiveness of Gamma Knife surgery (GKS) for metastatic brain tumors without adjuvant prophylactic whole-brain radiotherapy (WBRT). Salvage GKS was performed as the sole treatment for new distant lesions.

METHODS

Among 1127 patients in whom new brain metastases had been diagnosed, 97 who met one or more of the following three criteria were excluded from the study: any surgically inaccessible huge (>/= 35 mm) lesion; tumor number and size requiring an internal skull dose exceeding 10 J; or symptomatic carcinomatous meningitis. Thus, 1030 consecutive patients formed the basis for this study. Huge tumors were totally removed, whereas smaller lesions were treated with GKS. No adjuvant WBRT was given prior to GKS, and new distant lesions were appropriately retreated with GKS. Overall, neurological and new lesion-free survival curves were calculated and the prognostic values of covariates were obtained. In total, 1853 separate GKS sessions were required to treat 10,163 lesions.The patients' median overall survival period was 8.6 months. Neurological survival and new lesion-free rates at 1 year were 89.1 and 49.3%, respectively. In a multivariate analysis, the significant factors for poor prognosis were the development of more than four new brain metastases and active extracranial disease.

CONCLUSIONS

In meeting the goal of preventing neurological death and maintaining activities of daily living for patients with brain metastases, GKS alone provides excellent palliation without prophylactic WBRT. New distant lesions were quite well controlled with GKS salvage treatment alone.