Abstract: Noninvasive methods of determining breast cancer subtype in a subject are provided that employ newly identified biomarkers. Said methods comprise isolating a population of extracellular vehicles in a biofluid sample of a subject and detecting differential expression in one or more proteins or peptides therein. Such differential expression is compared to one or more expression profiles within a panel of biomarkers, with each expression profile in the panel associated with a subtype of breast cancer. Also provided are kits for detecting a subtype of breast cancer and/or identifying the recurrence thereof, each comprising an antibody, aptamer, or other detection means against the aforesaid biomarkers. Methods for monitoring treatment efficacy in a subject experiencing breast cancer using the same platforms are also provided.