Objective: To present the results of gamma knife surgery (GKS) for brain metastases from lung cancer, without whole-brain radiation therapy (WBRT), at Chiba Cardiovascular Center.
Methods: Four hundred and forty-three consecutive patients satisfying the following 5 criteria were analyzed: (1) no prior WBRT; (2) < or =25 lesions; (3) < or =4 tumors with a diameter of 20 mm or more; (4) no surgically inaccessible large (> or =35 mm) tumors, and (5) life expectancy exceeding 3 months. Large tumors were totally removed and all smaller lesions were treated with GKS. New lesions detected with follow-up magnetic resonance imaging were appropriately re-treated with GKS. Overall survival (OS), neurological survival (NS), qualitative survival (QS) and new lesion-free survival (NLFS) curves were calculated and the prognostic values of covariates were obtained.
Results: In total, 805 separate sessions were required to treat 4,626 lesions. The lung cancer histologies were adenocarcinoma in 294 patients, squamous cell in 52, small cell in 56, large cell in 9, and others/undetermined in 32. The median OS period was 8.9 months. On multivariate analysis, significant prognostic factors for OS were extracranial disease (risk factor: active), KPS score (< 70) and gender (male). NS and QS at 1 year were 86.9 and 80.1%, respectively. The only significant poor prognostic factor for NS was carcinomatous meningitis. A low Karnofsky performance status (KPS) score, numerous (> 10) brain lesions and carcinomatous meningitis were significant factors influencing QS. NLFS at 6 months was 70.0%.
Conclusion: In terms of NS and QS, GKS alone for metastatic brain tumors from lung cancer provides excellent palliation for selected patients without carcinomatous meningitis.