Analysis of long-term outcomes and prognostic factors in patients with non-small cell lung cancer brain metastases treated by gamma knife radiosurgery.

Object: The authors conducted a study to evaluate the long-term outcomes and prognostic factors for survival in a large series of patients treated by gamma knife surgery (GKS) for non-small cell lung cancer (NSCLC) brain metastases.

Methods: The study is based on the retrospective analysis of clinical and radiological records obtained during a 10-year period (1993-2003), concerning 836 lesions in 504 patients. The lesions were primary in 86% and recurrent 14% of the cases; they were solitary in 31%, single in 29%, and multiple in 40%. The mean follow-up period was 16 months (range 4-113 months). The most common histological types were adenocarcinoma (51%) and squamous cell carcinoma (27%). Dose planning parameters were as follows: mean target volume 6.2 cm3 (range 0.06-22.5 cm3); mean prescription dose 21.4 Gy (range 15.5-28 Gy); and mean number of isocenters 6.7 (range one-18). Progression-free and actuarial survival curves were calculated using the Kaplan-Meier method. The main factors affecting survival were determined by unimultivariate analysis (log-rank test and Cox proportional hazard models). Analysis of long-term outcomes seemed to confirm that GKS is a primary therapeutic option in these patients. The 1-year local tumor control rate was 94%. The overall median survival was 14.5 months, with extremely rewarding quality of life indices. The recursive partitioning analysis classification was the dominant prognostic factor.

Conclusions: Gamma knife surgery is a useful treatment for brain metastases from NSCLC.