Impact of multimodal, multidisciplinary care on clinical outcomes in patients with breast cancer and leptomeningeal carcinomatosis.

• DOI: 10.1200/jco.2025.43.16_suppl.e13043
• Publication Date: 2025-05-28T13:54:29Z
• Authors: Xiaojie Zhang; Hemali Batra-Sharma; Jessica Schulte; David Eric Piccioni; Jona Ashok Hattan...; Heather Orosco; Kathryn Ries Trin...; Jeffrey Steinberg; Kay T. Yeung; Alyssa Beck; Rebecca Arielle S...

e13043 Background: Leptomeningeal carcinomatosis (LMC) is a rare consequence of metastatic breast cancer (MBC) with dismal prognosis, historical 15-week median overall survival (OS). There no standard care treatment (tx), and paucity data on MBC subtype specific incidence prognosis. The impact newer CNS penetrating systemic (sys) tx like antibody drug conjugates (ADCs) multimodal BC related LMC prognosis underreported in contemporary literature. Here, we present real-world analysis cohort patients (pts) LMC. Methods: This single-institution retrospective study 48 pts diagnosed between 2016-2024, based radiographic features and/or positive cerebrospinal fluid (CSF) cytology or CSF circulating tumor cells (CTC). Pts consented to share information research biorepository (IRB 181755). We conducted chart review clinical features, tx, OS. Results: 25 (52%) had invasive ductal carcinoma, 14 (29%) lobular 4 (8%) metaplastic 2 (4%) inflammatory 3 (6%) mixed histology. 20 (42%) estrogen receptor (ER+)/human epidermal growth factor negative (HER2-) BC, HER2+ 24 (50%) triple (TNBC). Median age at diagnosis (dx) was 50 years. time from dx varied significantly by subtype: 24.5 months (mos) ER+/HER2-, 7 mos HER2+, 4.5 TNBC (p = 0.01). Prior ADCs (n 25) associated longer (21 vs. 8 mos, p 0.037). 32 (67%) confirmed CTC. 28 (58%) received intrathecal chemotherapy (ITC), 9 (19%) craniospinal irradiation (CSI), 26 (54%) whole brain radiation (WBRT), 18 (38%) ITC+ RT (CSI WBRT). OS 7.0 for 22.4 5.8 TNBC. Significantly seen ITC+/- vs alone (9.1 1.3 < 0.0001). post dx, all whom also (ITC RT), than ADC (13 5 0.002). Eastern Cooperative Group performance status (median 1) did not vary use. In naïve pre-LMC trend other sys (32 0.14). HER2 low ultralow who the addition trastuzumab deruxtecan 6) improved (23 5.5 0.02) compared +/- tx. Conclusions: historically has grim Our institutional experience supports that multimodal, multidisciplinary approach BC. Moreover, ADCs, when added Larger prospective studies are needed inform paradigms.