Natural history of OPMDs characterized
MedWire News: Potentially malignant disorders of the oral cavity (OPMDs) transform to invasive cancer in around 2.6% of cases, UK researchers have shown.
Their study, which appears in the Journal of Oral Pathology and Medicine, also found that the severity of dysplasia is a significant predictor for malignant transformation.
Saman Warnakulasuriya (King's College Dental Institute, London) and fellow researchers studied 1357 patients treated at Guy's Hospital between 1990 and 1999 and followed up for a mean 9.04 years.
All patients had OPMDs confirmed on biopsy, with specific diagnoses including keratosis/leukoplakia (24.7%), lichen planus (44.7%), lichenoid reaction (12.9%), discoid lupus erythematosus (1.9%), and chronic hyperplastic candidosis (3.8%).
In terms of baseline demographics, 60.9% were female and 30.0% were aged 47 years and under. The most common site for OPMD was the buccal mucosa and 15.1% of the cohort had oral epithelial dysplasia.
During follow-up, 35 patients (2.6%) developed oral cancer, the researchers report.
Patients who did and did not develop cancer differed in a number of ways, with malignant transformation being more likely in older patients, those with OPMDs in the floor of the mouth, and patients with oral leukoplakia.
Patients with malignant transformation were also more likely to have dysplasia, and the frequency of transformation rose with increasing severity of dysplasia. Rates of transformation were 1.0%, 4.8%, 15.7%, and 26.7% in patients with none, mild, moderate, and severe dysplasia at baseline.
Among the patients with dysplasia, transformation rates were higher during later periods of follow-up compared with earlier periods.
In Cox proportional analysis, dysplasia grade was a significant independent predictor for transformation to oral cancer, with a hazard ratio (HR) of 35.4 for high-grade versus no dysplasia. This association remained significant, albeit attenuated (HR=21.6), after adjusting for gender, age, anatomical site of OPMD, and diagnosis.
There were also significant trends between transformation rates and increasing dysplasia grades and increasing age.
Noting that the natural history of OPMDs is poorly understood, the researchers write: "In this study, we showed that dysplasia grade is an independent predictor of future risk of malignancy."
They add: "Based on this experience, we propose multicentre studies in Europe with a far larger sample size are needed to elucidate the natural history of malignant transformation of OPMDs and to identify predictive clinical and laboratory markers.
"A research consortium under the umbrella of the European Association of Oral Medicine is proposed."
By Joanna Lyford