Interestingly, the aberrant regulation of certain miRNAs has been shown to cut across several cancer types, for instance miR-21 is commonly up-regulated in breast, colon, lung, pancreas, prostate, stomach, cervical, ovarian, hepato-billiary and head and neck cancers as well as in B-cell lymphoma and chronic lymphocytic leukaemia [44,45,46,47,48], where different tumor suppressor mRNAs inclusive of programmed cell death 4 (Pdcd4), phosphatase and tensin homolog (PTEN) and tropomyosin 1 (alpha) (TPM1), to mention a few, are targeted. This evidence concerns the gene PDCD4 and head and neck cancer.