Basal-like tumor cells have a gene expression profile similar to the outer (basal) cells lining the mammary ducts and the basal layer of the skin. They account for approximately 10% of all breast cancers. Most basal-like breast cancers contain TP53 mutations and are triple negative (no expression of ER, PgR and HER2). This breast cancer subtype is aggressive and currently the only option of therapy is non-specific chemotherapy.