HOX Transcript Antisense RNA (HOTAIR), identified by Tang et al. in serum-derived EVs was markedly elevated in BC patient samples compared to controls with an AUC of 0.916 as opposed to 0.7378 for CA153.180 Interestingly, HOTAIR levels decreased post-surgery suggesting that they vary dynamically in concordance with tumor mass; HOTAIR could also act as a prognostic marker as its high expression was associated with poor overall and disease-free survival and non-responsiveness to therapy. Here, HOTAIR is linked to breast cancer.