It follows that if the occurrence of p53 over-expression can be considered specific in detecting oral lesions at risk of developing p53-positive tumours, the presence of low p53 values should be considered as non-informative for prognostic purposes, since it can not distinguish between lesions with a genetically reduced production of p53 at high risk of developing p53-negative tumours, and lesions with a physiological low p53 activity or lesions that follow different carcinogenic pathways in which the p53 abrogation does not play a role [7,11-22]. This evidence concerns the gene TP53 and neoplasm.