Background: Oral leukoplakia is a relatively common oral lesion that in a varying proportion of cases undergoes malignant transformation. Since most leukoplakias are asymptomatic, the need for treatment is primarily based on the precancerous nature of the lesion.
Objectives: To assess effectiveness, safety and acceptability of treatments for leukoplakia.
Search strategy: The following data bases were searched for relevant trials: MEDLINE, EMBASE, CancerLit, Biological Abstracts, Cochrane library. Hand searching was performed for the main oral medicine journals. Oral medicine experts were contacted through an European mailing list (EURORALMED).
Selection criteria: Randomised controlled trials (RCTs), enrolling patients with a diagnosis of oral leukoplakia, were included.
Data collection and analysis: Data were collected using a specific abstraction form. Malignant transformation of leukoplakia, demonstrated by histopathological examination, was the main outcome considered. Secondary outcomes included clinical resolution of the lesion and variation in dysplasia severity. The validity of included studies was assessed on the basis of the method of allocation concealment, blindness of the study and loss of participants. Data were analysed by calculating relative risk.
Main results: The possible effectiveness of surgical interventions, including laser therapy and cryotherapy, has apparently never been studied by means of a RCT. Fourteen potentially eligible RCTs of nonsurgical intervention were identified: five were excluded for different reasons, three were ongoing studies, leaving six studies to be included in the review. Vitamin A and retinoids were tested by four RCTs (224 patients), the other drugs tested were bleomycin (one study), mixed tea (one study) and beta carotene (one study). Malignant transformation was recorded in just two studies: none of the treatments tested showed a benefit when compared with the placebo. Treatment with beta carotene and vitamin A or retinoids, was associated with better rates of clinical remission, compared with placebo or absence of treatment. Whenever reported, a high rate of relapse was a common finding. Side effects of variable severity were often described; however, interventions were well accepted by patients, since drop-out rates were similar between treatment and control groups.
Reviewer's conclusions: To date there is no evidence of effective treatment in preventing malignant transformation of leukoplakia. Treatments may be effective in the resolution of lesion, however relapses and adverse effects are common.