Molecular findings in oral premalignant fields: update on their diagnostic and clinical implications.

The development of multiple oral tumours, seen in up to 30% of patients with a primary oral squamous cell carcinoma, is sometimes attributable to the presence of genetically altered premalignant fields and has important prognostic implications. Molecular techniques available for the definitive diagnosis of such a field (loss of heterozygosity analysis of 3p, 9p and 17p and study of TP53 tumour suppressor gene mutation) are expensive, complex and not universally available, hampering their routine application. Nevertheless, molecular diagnosis is essential for modern assessment of the risk of multiple tumours and for decisions on the appropriate preventive and therapeutic approaches. This article reviews current knowledge on molecular findings in premalignant fields in the oral cavity and oropharynx and provides an update on criteria for their identification, discussing the clinical and therapeutic implications.