WBRT usage in patients getting SRS for >5 brain metastases

Jonathan Knisely1, James Yu2, Veronica Chiang3

1Manhasset, United States 2Yale University School of Medicine and Yale Cancer Center 3New Haven, United States

Keywords: brain metastasis, outcome, radiotherapy, gamma knife, outcome

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     Stereotactic radiosurgery (SRS) of brain metastases improves short-to-intermediate term neurocognitive functioning in patients relative to an approach that combines SRS with whole brain radiation therapy (WBRT) in patients with 1-3 brain metastases. Using SRS alone increases the risk of requiring salvage CNS therapy, but has no impact upon survival, which is commonly held to be governed by extracranial disease status. WBRT is commonly recommended for patients with >4 brain metastases, and the appropriateness of SRS alone for this population is questioned.
     We evaluated a cohort of 103 patients treated with Gamma Knife SRS for >5 metastases to identify WBRT usage as a component of care for brain metastases.
     103 patients were identified. Lung, melanoma, breast, and kidney primaries were identified in 38, 33, 17, and 6 patients, respectively. The remaining 8 patients’ cancers had diverse histologic origins. 43 patients never got WBRT; 19 were still alive. 24 (56%) died without ever getting WBRT. 60 patients had WBRT; 18 were still alive. 45 of these 60 patients (75%) had WBRT prior to SRS for >5 metastases; only 15 (25%) had WBRT after SRS for >5 metastases.
     An institutional review board-approved retrospective analysis of the Yale Gamma Knife database identified patients treated with SRS for >5 brain metastases. WBRT’s use and timing relative to the dates of SRS and of death were recorded, along with demographic data. Survival was calculated using the method of Kaplan-Meier. Cox proportional hazards analysis was performed for variables associated with the hazard for death.
     The median survival from the date of radiosurgery for >5 brain metastases was 8.3 months. Overall survival was not impacted by WBRT administration. (p=0.965, HR=0.99 0.60-1.64.
     This was a retrospective study.
     75% of the patients who got SRS and WBRT had SRS for >5 brain metastases as a salvage therapy despite prior WBRT. Of the 58 patients who got SRS for >5 brain metastases without prior WBRT, only 15 (26%) subsequently received WBRT as salvage treatment. WBRT delivery did not affect overall survival.
     The neurocognitive sequelae of WBRT may potentially be avoided for most patients with >5 brain metastases.


Project Roles:

J. Knisely (), J. Yu (), V. Chiang ()