title: Long-term outcome of gamma knife radiosurgery for metastatic brain tumors originating from lung cancer.
abstract: BACKGROUND
  Gamma knife radiosurgery (GKRS) has emerged as an important treatment option for metastasis brain tumors (MBTs). However, the long-term outcome of GKRS on MBTs originating from lung carcinoma is not well understood. The treatment of MBTs derived from lung cancer with GKRS at our institution is reviewed.
  
  
  METHODS
  We performed a retrospective review (2000-2013) of 173 patients with MBTs from lung cancer who received GKRS. Out of 173 patients, 38 patients had recurrent tumors after microsurgical resection and whole brain radiotherapy (WBT).
  
  
  RESULTS
  GKRS in MBTs metastasized from lung carcinoma showed significant variations in tumor growth control (decreased in 79 [45.7%] patients, arrested growth in 54 [31.2%] patients, and increased tumor size in 40 [23.1%] patients). The median survival in the study population was 14 months. Overall survival after 3 years was 25%, whereas progression-free survival after 3 years was 45%. The predictive factors for improving survival in the patients with MBTs were recursive partitioning analysis (RPA) class I (P = 0.005), absence of hydrocephalus (P = 0.001), Karnofsky performance scale (KPS) >70 (P = 0.007), age ≤65 (P = 0.041), tumor size ≤3 cm (P = 0.023), controlled primary tumor (P = 0.049), and single number of MBTS (P = 0.044).
  
  
  CONCLUSIONS
  Long-term follow-up revealed that GKRS offers a high rate of tumor control and good overall survival period in both new and recurrent patients with MBTs originating from lung carcinoma. Thus, GKRS is an effective treatment option for new patients with MBTs from lung cancer, as well as an adjuvant therapy in patients with recurrent MBTs derived from lung cancer.
authors.affiliation: Department of Neurosurgery, LSU Health-Shreveport, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
authors.forename: Shyamal C
authors.initials: SC
authors.lastname: Bir
authors.affiliation: Department of Neurosurgery, LSU Health-Shreveport, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
authors.forename: Sudheer
authors.initials: S
authors.lastname: Ambekar
authors.affiliation: Department of Neurosurgery, LSU Health-Shreveport, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
authors.forename: Papireddy
authors.initials: P
authors.lastname: Bollam
authors.affiliation: Department of Neurosurgery, LSU Health-Shreveport, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
authors.forename: Anil
authors.initials: A
authors.lastname: Nanda
keywords: Gamma knife radiosurgery; long-term outcome; lung cancer; metastatic brain tumors; predictive factors