Malignant transformation rate of oral leukoplakia in an Australian population

Oral leukoplakia (OLK) is one of the most common oral potentially malignant lesions (OPMD) and is reported to undergo malignant transformation (MT) to oral squamous cell carcinoma (OSCC) at rates of between 0.13% and 34%. This study seeks to determine the proportion of OLK lesions that develop into OSCC in an Australian population and assess the risk factors associated with this transformation.

The study is a retrospective audit of patients from a private oral medicine clinic, diagnosed with OLK using clinical and histopathological data between 2006 and 2014. Patients were cross-matched with Cancer Registry data for OSCC, and the rate and time to malignant transformation were determined.

Oral leukoplakia patients with histopathological confirmation of their lesions underwent MT at a rate of 1.49% (3/202), with an average time to MT (TMT) of 5.2 years. When patients without histopathological confirmation were assessed, the MT rate was slightly less (1.30%; 4.9 years TMT). Patients who transformed were more likely to be older females with a history of smoking and alcohol use, with OLK present on the tongue or floor of mouth. The rate of oral epithelial dysplasia (OED) in the transformed group was surprisingly low (one third).

Oral leukoplakia is at a moderate risk of malignant transformation which can be reduced by careful management. Current tools for identifying high-risk OLK, including histopathological assessment of OED, may not capture all lesions that undergo MT and should be supplemented by unbiased molecular biomarkers.