Five-fraction stereotactic radiosurgery (SRS) for single inoperable high-risk non-small cell lung cancer (NSCLC) brain metastases.
BACKGROUND
Achieving durable local control while limiting normal tissue toxicity with definitive radiation therapy in the management of high-risk brain metastases remains a radiobiological challenge. The objective of this study was to examine the local control and toxicity of a 5-fraction stereotactic radiosurgical approach for treatment of patients with inoperable single high-risk NSCLC brain metastases.


METHODS
This retrospective analysis examines 20 patients who were deemed to have "high-risk" brain metastases. High-risk tumors were defined as those with a maximum diameter greater than 2 cm and/or those located within an eloquent cortex. Patients were evaluated by a neurosurgeon prior to treatment and determined to be inoperable due to tumor or patient characteristics. Patients were treated using the CyberKnife® SRS system in 5 fractions to a total dose of 30 Gy, 35 Gy, or 40 Gy.


RESULTS
Twenty patients with a median age of 65.5 years were treated from April 2010 to August 2014 in 5 fractions to a median total dose of 35 Gy. At a median follow up of 11.3 months local tumor control was observed in 18 of 20 metastases (90 %). Both local failures were observed in patients receiving a lower dose of 30 Gy. Median pre-treatment dexamethasone dose was 10 mg/day and median post-treatment nadir dose was 0 mg/day. Salvage intracranial therapy was required in 45 % of patients. Symptomatic radionecrosis was observed in 4 of 20 patients (20 %), two of which were treated to 40 Gy and the remainder to 35 Gy. Kaplan-Meier 1-year, 2-year, and median survival were calculated to be 45 %, 20 %, and 13.2 months, respectively.


CONCLUSIONS
Five-fraction SRS to a total dose of 35 Gy appears to be a safe and effective management strategy for single high-risk NSCLC brain metastases, while a total dose of 40 Gy leads to an excess risk of neurotoxicity.
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. jonathan.lischalk@gunet.georgetown.edu.
Jonathan W
JW
Lischalk
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. eko@georgetown.edu.
Eric
E
Oermann
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. SPC9@gunet.georgetown.edu.
Sean P
SP
Collins
Department of Neurosurgery, Georgetown University Hospital, Pasquerilla Healthcare Center (PHC), 7th floor, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. Mani.N.Nair@gunet.georgetoen.edu.
Mani N
MN
Nair
Department of Neurosurgery, Georgetown University Hospital, Pasquerilla Healthcare Center (PHC), 7th floor, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. Vikram.V.Nayar@gunet.georgetown.edu.
Vikram V
VV
Nayar
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. richabhasin93@gmail.com.
Richa
R
Bhasin
Department of Neurosurgery, Georgetown University Hospital, Pasquerilla Healthcare Center (PHC), 7th floor, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. JXV6@gunet.georgetown.edu.
Jean-Marc
JM
Voyadzis
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. sonali.rudra@gunet.georgetown.edu.
Sonali
S
Rudra
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. KXU2@gunet.georgetown.edu.
Keith
K
Unger
Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Lower Level Bles, 3800 Reservoir Road, N.W., Washington, DC, 20007, USA. COLLINSB@gunet.georgetown.edu.
Brian T
BT
Collins
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies