Single-center retrospective cohort study of demographic and clinical characteristics of patients with metastatic breast cancer and leptomeningeal disease

A retrospective cohort study at the University of California San Francisco investigated demographic and clinical characteristics of patients with metastatic breast cancer (mBC) and leptomeningeal disease (LMD). Among 111 patients with mBC and LMD from 2000 to 2024, 47.7% had HR+/HER2- subtype, 27.0% had HER2+ subtype, and 25.2% had TNBC subtype. Median time from diagnosis mBC to LMD was 16.4 months (range 0-101.3). After the LMD diagnosis, most patients received systemic therapy (59.5%) and/or CNS-directed therapy (84.7%). Among all patients, median overall survival from LMD diagnosis was 4.1 months (range 0.1-78.1), which varied by subtype and therapy. Patients diagnosed with LMD from 2015 lived longer after LMD diagnosis than those diagnosed from 2000 to 2014. On multivariable analysis, having TNBC was associated with shorter OS from LMD diagnosis (versus other subtypes HR 2.03; p=0.004). The authors conclude that this is one of the largest case series of patients with mBC and LMD. The overall median OS from LMD diagnosis was short. Patients with LMD diagnosis from 2015 to 2024 lived longer than those diagnosed from 2000 to 2014.