In a systematic review and meta-analysis reported in JAMA Oncology, Chen et al found that stereotactic radiosurgery for brainstem metastases was effective and safe, with outcomes comparable to those observed with stereotactic radiosurgery for nonbrainstem brain metastases.
A literature search was performed for English-language studies of stereotactic radiosurgery for brainstem metastases with at least 10 patients that reported one or more outcomes of interest published through December 2019.
A total of 32 retrospective studies including 1,446 patients with 1,590 brainstem metastases treated with stereotactic radiosurgery published between 1999 and 2019 were included in the analysis. The I2 cutoff values of 25%, 50%, and 75% distinguished low, low-moderate, moderate-high, and high heterogeneity across studies for particular outcomes.
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Local control at 1 year was 86% (95% confidence interval [CI] = 83%88%; I2 = 38%, P = .12 for heterogeneity) in 1,410 patients across 31 studies, the objective response rate was 59% (95% CI = 47%–71%; I2 = 88%, P < .001 for heterogeneity) in 642 patients across 17 studies, and symptom improvement was 55% (95% CI = 47%–63%; I2 = 41%, P = .06 for heterogeneity) in 323 patients across 13 studies.
Overall survival at 1 year was 33% (95% CI = 30%–37%; I2 = 35%, P = .04 for heterogeneity) in 1,254 patients across 27 studies; overall survival at 2 years was 13% (95% CI = 11%–16%; I2 = 30%, P = .10 for heterogeneity) in 959 patients across 22 studies.
Deaths from brainstem metastases progression after stereotactic radiosurgery accounted for 2.7% of 703 deaths across 19 studies. The rate of neurologic death was 24% (95% CI = 19%–31%; I2 = 62%, P < .001 for heterogeneity), accounting for 643 deaths across 17 studies.
The rate of treatment-related grade ≥ 3 toxicity was 2.4% (95% CI = 1.5%–3.7%; I2 = 33%) in 1,421 patients across 31 studies.
Compared with pooled results of six published prospective trials of stereotactic radiosurgery in nonbrainstem brain metastases, findings in patients with brainstem metastases were similar for rates of neurologic death (24% vs 22%, P = .74), local control (86% vs 81%), and grade ≥ 3 toxicity (2.4% vs 5.1%). The objective response rate of 59% with stereotactic radiosurgery in brainstem metastases compared favorably with rates reported in 43 prospective trials of immunotherapy or targeted therapy in nonbrainstem brain metastases (17%–56%).
The investigators concluded: “Results of this systematic review and meta-analysis show that stereotactic radiosurgery for brainstem metastases was associated with effectiveness and safety and was comparable to stereotactic radiosurgery for nonbrainstem brain metastases, suggesting that patients with brainstem metastases should be eligible for clinical trials of stereotactic radiosurgery. In this analysis, patients treated with stereotactic radiosurgery for brainstem metastases rarely died from brainstem metastases progression and often experienced symptomatic improvement. Given the apparent safety and efficacy of stereotactic radiosurgery for brainstem metastases in the context of acute morbidity or death from brainstem metastases growth, consideration of stereotactic radiosurgery at the time of enrollment on emerging trials of targeted therapy for nonbrainstem brain metastasis should be considered.”
David R. Raleigh, MD, PhD, of the Departments of Radiation Oncology and Neurological Surgery, and Steve E. Braunstein, MD, PhD, of the Department of Radiation Oncology, University of California, San Francisco, are the corresponding authors for the JAMA Oncology article.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.