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Gamma knife radiosurgery for brain metastasis of nonsmall cell lung cancer: Is there a difference in outcome between morning and afternoon treatment?
Author(s) -
Rahn Douglas A.,
Ray Dibyendu K.,
Schlesinger David J.,
Steiner Ladislau,
Sheehan Jason P.,
O'Quigley John M.,
Rich Tyvin
Publication year - 2010
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.25423
Subject(s) - medicine , radiosurgery , brain metastasis , lung cancer , surgery , proportional hazards model , log rank test , radiation therapy , metastasis , cancer
BACKGROUND: Circadian cell‐cycle progression causes fluctuating radiosensitivity in many tissues, which could affect clinical outcomes. The purpose of this study was to determine whether outcomes of single‐session gamma knife radiosurgery (GKRS) for metastatic nonsmall cell lung cancer (NSCLC) differ based on treatment time. METHODS: Fifty‐eight patients received GKRS between 10:00 am and 12:30 pm and 39 patients received GKRS between 12:30 pm and 3:00 pm. The mean peripheral dose was 18.6 Gy. The mean tumor size was 7.3 cm 3 . Magnetic resonance imaging was used to score local control at 3 months. Cause of death (COD) was categorized as central nervous system (CNS)‐related or systemic. RESULTS: Demographic and disease characteristics of the 2 groups were similar. Local control at 3 months was achieved in 97% (35/36) of patients who underwent GKRS early in the day versus 67% (8/12) of patients who underwent GKRS later in the day (chi‐square, P = .014). Early GKRS was associated with better survival (median 9.5 months) than late GKRS (median 5 months) (Kaplan‐Meier log‐rank test, P = .025). Factors contributing to better survival in a Cox regression model included early treatment time ( P = .004) and recursive partition analysis class ( P < .001). Cause of death in the early treatment group was CNS‐related in 6% (3/47) of patients versus 24% (8/34) of patients in the late treatment group (chi‐square test, P = .026). CONCLUSIONS: GKRS for metastatic NSCLC had better local control, better survival, and a lower rate of CNS‐related cause of death when given earlier in the day versus later in the day. These retrospective data should encourage future study in brain radiosurgery and non‐CNS stereotactic body radiotherapy series. Cancer 2011. © 2010 American Cancer Society.