Stereotactic radiosurgery of the postoperative resection cavity for brain metastases: prospective evaluation of target margin on tumor control.
OBJECTIVE
Given the neurocognitive toxicity associated with whole-brain irradiation (WBRT), approaches to defer or avoid WBRT after surgical resection of brain metastases are desirable. Our initial experience with stereotactic radiosurgery (SRS) targeting the resection cavity showed promising results. We examined the outcomes of postoperative resection cavity SRS to determine the effect of adding a 2-mm margin around the resection cavity on local failure (LF) and toxicity.


METHODS
We retrospectively evaluated 120 cavities in 112 patients treated from 1998-2009. Factors associated with LF and distant brain failure (DF) were analyzed using competing risks analysis, with death as a competing risk. The overall survival (OS) rate was calculated by the Kaplan-Meier product-limit method; variables associated with OS were evaluated using the Cox proportional hazards and log rank tests.


RESULTS
The 12-month cumulative incidence rates of LF and DF, with death as a competing risk, were 9.5% and 54%, respectively. On univariate analysis, expansion of the cavity with a 2-mm margin was associated with decreased LF; the 12-month cumulative incidence rates of LF with and without margin were 3% and 16%, respectively (P=.042). The 12-month toxicity rates with and without margin were 3% and 8%, respectively (P=.27). On multivariate analysis, melanoma histology (P=.038) and number of brain metastases (P=.0097) were associated with higher DF. The median OS time was 17 months (range, 2-114 months), with a 12-month OS rate of 62%. Overall, WBRT was avoided in 72% of the patients.


CONCLUSIONS
Adjuvant SRS targeting the resection cavity of brain metastases results in excellent local control and allows WBRT to be avoided in a majority of patients. A 2-mm margin around the resection cavity improved local control without increasing toxicity compared with our prior technique with no margin.
Department of Neurosurgery, Stanford University Medical Center, Stanford, California 94305-5847, USA.
Clara Y H
CY
Choi
Steven D
SD
Chang
Iris C
IC
Gibbs
John R
JR
Adler
Griffith R
GR
Harsh
Robert E
RE
Lieberson
Scott G
SG
Soltys
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001932:Brain Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000473:pathology / Q000556:secondary / Q000601:surgery*; D016371:Cranial Irradiation / Q000009:adverse effects / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000401:mortality / Q000601:surgery; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D016879:Salvage Therapy / Q000379:methods; D015996:Survival Rate; D013997:Time Factors; D047368:Tumor Burden; D055815:Young Adult