title: Malignant transformation of oral potentially malignant disorders in males: a retrospective cohort study.
abstract: BACKGROUND
  Oral squamous cell carcinoma could be preceded by clinically evident oral potentially malignant disorders (OPMDs). Transformation of OPMDs to cancer has been studied in several population groups. It is difficult to undertake comparisons across populations due to variations in the methods of computation of malignancy rates among different studies. The aim of our study was to estimate the rate of malignant transformation of OPMDs taking into account the duration of follow-up and to identify the significant factors indicative of malignant potential.
  
  
  METHODS
  A total of 148 male patients with OPMDs were included. They were selected among all consecutive subjects registered at the maxillofacial clinic at a medical hospital in Kaohsiung, Taiwan. The mean follow up period was 37.8 months.
  
  
  RESULTS
  The malignant transformation rate was highest in subjects diagnosed with oral epithelial dysplasia. In this group the transformation rate was 7.62 per 100 persons-year. The rate in the group with verrucous hyperplasia (VH) was 5.21 per 100 persons-year, and in those with hyperkeratosis or epithelial hyperplasia was 3.26 per 100 persons-year. The anatomical site of OPMDs was the only statistically significant variable associated with malignancy. The hazard rate ratio (HRR) was 2.41 times for tongue lesions when compared with buccal lesions.
  
  
  CONCLUSIONS
  The reported discrepancies of malignant transformation of OPMDs involve the follow-up time to cancer development and hence it is preferable to use a time-to-event estimation for comparisons. We found that malignant transformation of OPMDs involving the tongue was significantly higher than in other anatomical subsites after adjusting for the clinicopathological type or lifestyle factors at diagnosis.
authors.affiliation: Division of Oral and Maxillofacial Surgery, Department of Dentistry, Kaoshiung Medical University Hospital, Kaohsiung, Taiwan, Republic of China. psho@kmu.edu.tw
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Ho
authors.forename: Pai-Li
authors.initials: PL
authors.lastname: Chen
authors.forename: Saman
authors.initials: S
authors.lastname: Warnakulasuriya
authors.forename: Tien-Yu
authors.initials: TY
authors.lastname: Shieh
authors.forename: Yun-Kwan
authors.initials: YK
authors.lastname: Chen
authors.forename: I-Yueh
authors.initials: IY
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D002471:Cell Transformation, Neoplastic; D015331:Cohort Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology; D014062:Tongue Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology; D055815:Young Adult