title: Evaluation of Potential Risk Factors that contribute to Malignant Transformation of Oral Lichen Planus: A Literature Review.
abstract: OBJECTIVE
  Many studies have suggested that a lesion originally diagnosed as oral lichen planus (OLP) has different possibilities of undergoing malignant transformation in time, although these findings remain a controversial issue; for example, some studies reported different values of potential malignancy of OLP.
  
  
  BACKGROUND
  World Health Organization (WHO) classifies OLP as a "potentially malignant disorder" with unspecified malignant transformation risk, and suggests that OLP patients should be closely monitored. Numerous studies have attempted to confirm the malignant transformation potential of OLP.
  
  
  RESULTS
  The Cochrane Controlled Trials Register, Medline and EMBASE databases, PubMed, Google Scholar, Ovid, Up To Date, BMJ Clinical Evidence, MD Consult, and Science Direct were searched for papers published between 1997 and 2015. The medical subject heading search terms were "lichen planus," "oral lichen planus," "erosive oral lichen planus," "dysplasia," "oral precancerous condition," "oral premalignant condition," oral cancer, oral squamous cell carcinoma (OSCC), and atrophic lichen planus. A total of 120 English language abstracts were reviewed, and 50 relevant articles identified. Because of the extensive literature on the association between OLP and SCC, we have divided the data into genetic and non-genetic factors for more accurate assessment.
  
  
  CONCLUSIONS
  In this evidence base, malignant transformation ranges from 0 to 37% with a mean of 4.59%. The highest rate of malignancy was noted in erythematosus and erosive lesions. In this way, follow-up of OLP patients could be carried out more efficiently and appropriately.
  
  
  CONCLUSIONS
  Oral lichen planus is a premalignant lesion. All types of OLP in any site of oral mucosa must be monitored regularly.
authors.affiliation: ProfessorDental Research Center, Dental Research Institute, Tehran University of Medical Sciences; Department of Oral Medicine Faculty of Dentistry, Tehran University of Medical Sciences Tehran, Iran, Phone: +42794151, e-mail: aghahose@tums.ac.ir.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Agha-Hosseini
authors.affiliation: Dental Research Center, Dental Research Institute, Tehran University of Medical Sciences; Department of Oral Medicine Faculty of Dentistry, Tehran University of Medical Sciences Tehran, Iran.
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Sheykhbahaei
authors.affiliation: Dental Research Center, Dental Research Institute, Tehran University of Medical Sciences; Department of Oral Medicine Faculty of Dentistry, Tehran University of Medical Sciences Tehran, Iran.
authors.forename: Maryam-Sadat
authors.initials: MS
authors.lastname: SadrZadeh-Afshar
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002471:Cell Transformation, Neoplastic; D006801:Humans; D017676:Lichen Planus, Oral / Q000473:pathology*; D009062:Mouth Neoplasms / Q000473:pathology*; D011230:Precancerous Conditions / Q000473:pathology*; D012307:Risk Factors
keywords: Dysplasia; Malignancy; Oral lichen planus; Precancerous condition; Squamous cell carcinoma.