title: Marked variation in malignant transformation rates of oral leukoplakia.
abstract: METHODS
  Searches were carried out in the Medline, Embase and PubMed databases in July 2014 with a date range, 1960-2013.
  
  
  METHODS
  Observational cohort studies (either prospective or retrospective) were included. Studies following identical cohorts, case control studies, clinical trials, interventional studies, laboratory studies, experimental studies, studies with no follow-up data, studies of pre-leukoplakia or snuff-induced lesions were excluded.
  
  
  METHODS
  The databases were searched by one reviewer who also screened the studies and evaluated them against the inclusion criteria. Final decision on both inclusion and exclusion of the papers was agreed upon by both authors.
  
  
  RESULTS
  A total of 24 studies were included in this review, involving 12,103 patients. Of the 24 studies included 14 were retrospective. Studies were analysed by subgroup, allowing the authors to identify the rate of malignant transformation as 14.9% with a range of 0.13% to 34%. Only 11 studies gave information on the site of malignant transformation; the most common site was the buccal mucosa. For buccal mucosa the malignant transformation was 3.53%, compared to 24.22% for the tongue. Homogenous oral leukoplakia (OL) was most common, however non-homogenous types showed a higher rate of transformation of 13.1%. There was an increased risk of malignant transformation with age. Most studies demonstrated that there is a higher risk of transformation in the female population.
  
  
  CONCLUSIONS
  Malignant transformation rate of OL varies from 0.13 to 34% across the 24 studies reviewed here. The authors identified clear risk factors for malignant transformation of oral leukoplakia, including location (tongue), appearance (non-homogenous), increased age and female gender. There was little evidence that surgical intervention had any benefit in reducing the risk of transformation.
authors.affiliation: Dublin Dental University Hospital, Dublin, Ireland.
authors.forename: Aisling
authors.initials: A
authors.lastname: Anderson
authors.affiliation: Dublin Dental University Hospital, Dublin, Ireland.
authors.forename: Nurul
authors.initials: N
authors.lastname: Ishak
mesh_terms: D002471:Cell Transformation, Neoplastic; D055094:Evidence-Based Dentistry; D005260:Female; D006801:Humans; D007972:Leukoplakia, Oral / Q000473:pathology*; D008297:Male; D009061:Mouth Mucosa / Q000473:pathology; D012307:Risk Factors; D012737:Sex Factors