Additionally, recent evidence indicates that the expression of DICER1, which is the key enzyme required for the biogenesis of microRNAs and small interfering RNAs and is essential for both mammalian development and cell differentiation is associated with hormone receptor status and cancer subtype in breast tumours and that its downregulation may be related to the metastatic spread of tumours [30]. This evidence concerns the gene DICER1 and breast neoplasm.