ESR1 and ductal breast carcinoma in situ: miR-16, miR-30b, and miR-93 have specific exosome packaging. Levels of miR-93 were significantly enriched in exosomes from DCIS patients rather than BC patients. Levels of miR-16 were high in patients with ER+ (n = 85) when compared to TNBC patients (n = 24).