Upfront radiosurgery for brain metastases: does size matter?

Anna Likhacheva1, Chelsea Pinnix2, Neil Parikh3, Pamela Allen2, Mary McAleer2, Nandita Guha-Thakurta4, Prabhu Sujit5, Dershan Luo1, Paul Brown2, Eric L. Chang2

1Houston, United States 2Department of Radiation Oncology, UT MDACC, Houston, Texas USA 3Baylor School of Medicine, Houston, Texas USA 4Department of Diagnostic Radiology, UT MDACC, Houston, Texas USA 5Department of Neurosurgery, UT MDACC, Houston, Texas USA

Keywords: brain metastasis, outcome, gamma knife, radiosurgery, brain tumor

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     The number of brain metastases (BM) is a major consideration in determining patient eligibility for stereotactic radiosurgery (SRS). 
     The purpose of this study was to evaluate whether in addition to number, BM volume carries a prognostic significance in patients treated with upfront SRS.
     We retrospectively identified 252 adult patients who underwent SRS for upfront treatment of BM between 2009 and 2010.
     224 patients were treated with Leksell Gamma Knife and 28 with LINAC delivery. The exclusion criteria were previous craniotomy and/or WBRT. Most common histologies were non-small cell lung cancer (34%), melanoma (30%), and breast carcinoma (16%). Number and volume of BM were measured at SRS. Median number was 2 (range: 1-13) and median total tumor volume was 0.9 cm3 (range 0.3-22.9 cm3). The median dose was 20 Gy (range 15-25 Gy). SRS was used as sole management (62% of patients), or in combination with salvage treatment with SRS (22%), WBRT (13%) or neurosurgery (3%). Median follow-up was 7.5 months.
     Median overall survival (OS) was 11.1 months. One year local control (LC) rate was 94.2%. The median time to distant brain failure (DBF) was 9.2 months. Both volume and number of treated sites were significant prognostic factors for OS (p<0.001) on multivariate analysis. For instance, total treatment volume > 2cc was equally predictive of OS as treatment of ?3 metastases (HR=1.9 for both). Although on univariate analysis, total volume and largest lesion volume appeared to carry a similar prognosis in terms of OS (HR: 1.10 and 1.14, p<0.001), multivariate analysis revealed that volume of the largest lesion was not prognostic. Treatment volume was prognostic for LC (p<0.001). A cut-off point for the number of metastases that was prognostic was ?3. No association was found between LC and the number of treated lesions. DBF was associated with neither volume nor number of BM.
     This was a retrospective study.
     Treatment volume > 2cc and number of BM > 3 are both predictive of worse OS in patients being treated with upfront SRS for new BM. 
     Total volume and number of BM should be considered as important factors in selecting appropriate candidates for upfront SRS.


Project Roles:

A. Likhacheva (), C. Pinnix (), N. Parikh (), P. Allen (), M. McAleer (), N. Guha-Thakurta (), P. Sujit (), D. Luo (), P. Brown (), E. Chang ()