Serum exosomal lncRNA XIST is a potential non‐invasive biomarker to diagnose recurrence of triple‐negative breast cancer

Exosomal lncRNAs secreted by cancer cells can serve as potential biomarkers in the diagnosis and prognosis of various tumours. Here, we are committed to explore the diagnostic and prognostic value of serum exosomal XIST secreted by tumour cells to predict recurrence in patients with triple‐negative breast cancer (TNBC). Significant increments in XIST and exo‐XIST from tumour tissues and blood serum were found in reoccurring TNBC patients by comparison with non‐recurrences. Levels of serum exo‐XIST were only significantly increased in TNBC recurrence and no association with other clinicopathological parameters. Additionally, serum exo‐XIST levels could be served as an assessment of change in the load of triple‐negative breast cancer. Expressions of exo‐XIST were markedly decreased after resection of the primary breast tumours and obviously elevated at the time of recurrence. Finally, an obvious association was identified between serum exo‐XIST levels and a poorer overall survival (OS) in TNBC patients. Levels of serum exo‐XIST may serve as a diagnostic and prognostic biomarker to predict the recurrent TNBC‐loading status.