{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T13:41:43Z","timestamp":1793108503799,"version":"4.5.0"},"reference-count":26,"publisher":"Springer Science and Business Media LLC","issue":"3","license":[{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T00:00:00Z","timestamp":1791331200000},"content-version":"vor","delay-in-days":6,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Breast Cancer Res Treat"],"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>Brain-only metastatic breast cancer (BO-MBC), defined as breast cancer with brain metastases (BrM) in the absence of extracranial metastatic disease (ECM), may represent a distinct metastatic phenotype. We characterized clinicopathologic features, treatment patterns, and outcomes of BO-MBC and evaluated associations between metastatic pattern, treatment, and survival.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Patients with isolated BrM at our institution were evaluated for intracranial progression-free survival (iPFS), extracranial progression-free survival (ePFS), leptomeningeal disease-free survival (LMD-PFS), and overall survival (OS). Patients with MBC diagnosed between 2010 and 2020 were identified from the NCDB and classified as BO-MBC or BrM with concurrent ECM (BrM\u2009+\u2009ECM). Overlap propensity score-weighted Cox models evaluated associations between metastatic pattern, treatment, and OS.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      In the institutional cohort (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200930), intracranial progression was the predominant pattern of failure, with median iPFS of 14.6 months versus ePFS of 30.4 months. In the NCDB cohort (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u20098,909), 1,540 patients (17.3%) had BO-MBC. Compared with BrM\u2009+\u2009ECM, BO-MBC was associated with node-negative, triple-negative, and fewer HR+\/HER2- disease (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). BO-MBC patients were more likely to receive brain radiotherapy (54.8% vs. 41.0%,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001) but less likely to receive systemic therapy (67.2% vs. 74.5%,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). In unadjusted Kaplan-Meier analyses, BO-MBC was associated with longer median OS than BrM\u2009+\u2009ECM (12.5 months [95% CI, 3.6\u201343.6] vs. 10.6 months [95% CI, 2.6\u201333.8]). Systemic therapy was associated with improved OS, with the greatest benefit in BO-MBC (adjusted HR 0.22, 95%CI 0.18\u20130.27). Brain radiotherapy was associated with improved OS in BO-MBC but not BrM\u2009+\u2009ECM.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>BO-MBC may represent a distinct clinical subgroup with unique clinicopathologic characteristics, treatment patterns, and improved survival. Intracranial progression predominated despite durable extracranial control, supporting optimized brain-directed management and prospective investigation of BO-MBC as a unique metastatic phenotype.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Clinical trial number<\/jats:title>\n                    <jats:p>Not applicable.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s10549-026-08092-3","type":"journal-article","created":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T07:41:24Z","timestamp":1791358884000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Brain-only metastatic breast cancer as a distinct clinical entity: evidence from national and institutional cohorts with implications for radiation therapy"],"prefix":"10.1007","volume":"219","author":[{"given":"Marshall","family":"Harrell","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tugce","family":"Kutuk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yevgeniya","family":"Gokun","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rituraj","family":"Upadhyay","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sachin R.","family":"Jhawar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel","family":"Stover","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nicole","family":"Williams","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Margaret E.","family":"Gatti-Mayes","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gina","family":"Sizemore","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heather","family":"LeFebvre","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John C.","family":"Grecula","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raju R.","family":"Raval","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raj","family":"Singh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simeng","family":"Zhu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dukagjin M.","family":"Blakaj","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arnab","family":"Chakravarti","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua D.","family":"Palmer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sasha J.","family":"Beyer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,10,7]]},"reference":[{"issue":"6","key":"8092_CR1","doi-asserted-by":"publisher","first-page":"894","DOI":"10.1093\/neuonc\/noaa285","volume":"23","author":"M Kuksis","year":"2021","unstructured":"Kuksis M et al (2021) The incidence of brain metastases among patients with metastatic breast cancer: a systematic review and meta-analysis. 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