我们对大规模的、回顾性队列的转移性乳腺癌（MBC）患者的脑转移的危险因素和生存情况进行了表征，并将其作为首个和唯一的疾病发生部位。在2005年至2019年期间，在一个四级机构接受放射治疗的脑转移MBC患者被辨识出来。对于脑转移MBC但无同时伴发颅内膜病变（ECM）或脑膜炎（LMD）的患者，我们将其归类为仅限于脑部。我们研究了与仅限于脑部的MBC、仅限于脑部特异性无进展生存期（bsPFS）和总生存期（OS）相关的因素。共分析了691名MBC和脑转移患者。其中，67名患者（占总数的9.7%，n = 67/691）呈现出仅限于脑部的MBC，并且没有同时伴发ECM/LMD。在这个亚组中，40名患者（占总数的5.8%，n = 40/691）在随访中没有出现任何ECM或LMD，而17名患者（占总数的2.5%）出现了LMD，10名患者（占总数的1.4%）出现了ECM，随访中位数为8个月（IQR 2-35）。与同时伴发ECM/LMD的患者相比，仅限于脑部的MBC患者更有可能出现单个脑转移灶[OR 3.41 (1.62-7.19)，p = 0.001]，以及HER2阳性[OR 3.3 (1.13-9.65)，p = 0.03]或TNBC[OR 4.09 (1.42-11.74)，p = 0.009]亚型。与同时伴发ECM/LMD的患者相比，呈现仅限于脑部的MBC的患者具有显著更长的OS [HR 0.45 (0.22-0.86)，p = 0.008] 和趋于更长的bsPFS [HR 0.67 (0.44-1.03)，p = 0.05]。与有ECM的患者相比，具有仅限于脑部的MBC的患者具有更长的bsPFS和OS。HER2阳性和TNBC患者相比，HR+/HER2-的MBC患者更有可能出现仅限于脑部的疾病情况。 © 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

We characterized the risk factors and survival of metastatic breast cancer (MBC) patients with brain metastases (BrM) as the first and only site of disease in a large, retrospective cohort.MBC patients treated for BrM with radiation at a quaternary institution between 2005 and 2019 were identified. MBC patients with BrM but without concurrent extracranial metastases (ECM) or leptomeningeal disease (LMD) were classified as brain-only. Factors associated with brain-only MBC, brain-specific progression free survival (bsPFS) and overall survival (OS) were investigated.A total of 691 patients with MBC and BrM were analyzed. Among them, 67 patients (9.7%, n = 67/691) presented with brain-only MBC without concurrent ECM/LMD. Within this subgroup, 40 patients (5.8%, n = 40/691) remained free of any ECM or LMD, while 17 patients (2.5%) developed LMD, and 10 patients (1.4%%) developed ECM with a median follow-up of 8 months (IQR 2-35). Patients with brain-only MBC were more likely to have a single BrM [OR 3.41 (1.62-7.19), p = 0.001] and either HER2+ [OR 3.3 (1.13-9.65), p = 0.03] or TNBC [OR 4.09 (1.42-11.74), p = 0.009] subtypes. Patients who presented with brain-only MBC also had significantly longer OS [HR 0.45, (0.22-0.86), p = 0.008] and a trend toward longer bsPFS [HR 0.67 (0.44-1.03), p = 0.05] compared to those with concurrent ECM/LMD.Patients with brain-only MBC had a longer bsPFS and OS than those with ECM. Patients with HER2+ and TNBC were more likely to have brain-only disease compared to those with HR+/HER2- MBC.© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.