Postoperative stereotactic radiosurgery without whole-brain radiation therapy for brain metastases: potential role of preoperative tumor size.
OBJECTIVE
Radiation therapy following resection of a brain metastasis increases the probability of disease control at the surgical site. We analyzed our experience with postoperative stereotactic radiosurgery (SRS) as an alternative to whole-brain radiotherapy (WBRT), with an emphasis on identifying factors that might predict intracranial disease control and overall survival (OS).


METHODS
We retrospectively reviewed all patients through December 2008, who, after surgical resection, underwent SRS to the tumor bed, deferring WBRT. Multiple factors were analyzed for time to intracranial recurrence (ICR), whether local recurrence (LR) at the surgical bed or "distant" recurrence (DR) in the brain, for time to WBRT, and for OS.


RESULTS
A total of 49 lesions in 47 patients were treated with postoperative SRS. With median follow-up of 9.3 months (range, 1.1-61.4 months), local control rates at the resection cavity were 85.5% at 1 year and 66.9% at 2 years. OS rates at 1 and 2 years were 52.5% and 31.7%, respectively. On univariate analysis (preoperative) tumors larger than 3.0 cm exhibited a significantly shorter time to LR. At a cutoff of 2.0 cm, larger tumors resulted in significantly shorter times not only for LR but also for DR, ICR, and salvage WBRT. While multivariate Cox regressions showed preoperative size to be significant for times to DR, ICR, and WBRT, in similar multivariate analysis for OS, only the graded prognostic assessment proved to be significant. However, the number of intracranial metastases at presentation was not significantly associated with OS nor with other outcome variables.


CONCLUSIONS
Larger tumor size was associated with shorter time to recurrence and with shorter time to salvage WBRT; however, larger tumors were not associated with decrements in OS, suggesting successful salvage. SRS to the tumor bed without WBRT is an effective treatment for resected brain metastases, achieving local control particularly for tumors up to 3.0 cm diameter.
Section of Radiation Oncology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA. Alan.C.Hartford@Hitchcock.org
Alan C
AC
Hartford
Anthony J
AJ
Paravati
William J
WJ
Spire
Zhongze
Z
Li
Lesley A
LA
Jarvis
Camilo E
CE
Fadul
C Harker
CH
Rhodes
Kadir
K
Erkmen
Jonathan
J
Friedman
David J
DJ
Gladstone
Eugen B
EB
Hug
David W
DW
Roberts
Nathan E
NE
Simmons
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001932:Brain Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy / Q000556:secondary / Q000601:surgery*; D016371:Cranial Irradiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016879:Salvage Therapy / Q000379:methods; D016019:Survival Analysis; D013997:Time Factors; D047368:Tumor Burden; D055815:Young Adult