Integrated extracellular-vesicle miRNA datasets GSE197020, GSE141326, GSE241784 and GSE241785 spanning controls, breast cancer and molecular subtypes (HR⁺ Luminal A/B, HR⁺/HER2⁺ and TNBC) to identify reproducible circulating miRNA signatures across heterogeneous cohorts. The workflow combined differential-expression meta-analysis and pooled effect-size estimation with MINT sPLS-DA supervised integration, ROC-based performance assessment and pathway enrichment, prioritizing miRNAs supported by both cross-cohort consistency and subtype-discriminative capacity rather than single-dataset associations