title: Factors affecting carbon dioxide laser treatment for oral precancer: a patient cohort study.
abstract: BACKGROUND
  Although the benefits of CO(2) laser surgery in oral precancer management have been evaluated, little consideration has been given to the factors which may influence treatment outcome, especially amongst patients developing recurrence or malignant transformation.
  
  
  METHODS
  Seventy eight patients (51 males, 27 females; mean age 57.8 years) undergoing CO(2) laser excision of single, new dysplastic oral precancer lesions (OPLs) were followed up for a minimum of 2 years and the influence of clinico-pathological parameters, socio-demographic factors and the presence or absence of residual dysplasia in excision margins upon clinical outcome were examined.
  
  
  RESULTS
  Seventy three percent of patients were smokers and 78% consumed alcohol regularly. The majority of lesions were leukoplakias arising in the floor of mouth and ventro-lateral tongue and moderate or severe dysplasia accounted for 86% of histopathological diagnoses. Patient follow up ranged from 24 to 119 months (mean 58 months). Sixty four percent of patients were disease free at most recent clinical follow up, whilst 32% developed local recurrent dysplasia or new site dysplasia with 4% developing oral squamous cell carcinoma (but at sites distinct from their initial OPL). Excision margins were clear in 55% of cases, but 19% showed mild, 21% moderate and 5% severe dysplasia on histopathological examination. No statistically significant associations were seen between patients' age, gender, lesion appearance, site of origin, histopathological grading, presence of dysplasia in resection margins, or alcohol consumption and clinical outcome. Smokers, however, were at significantly higher risk of dysplasia recurrence compared to ex-smokers or non-smokers (P = 0.04).
  
  
  CONCLUSIONS
  In the absence of agreed treatment protocols for OPLs, we recommend CO(2) laser surgery as an effective treatment modality offering precise lesion excision, full histopathological assessment, minimal post-operative morbidity and a 64% disease free clinical outcome. Regular patient follow up is encouraged due to the persistence of field cancerisation effects.
authors.affiliation: Oral & MaxilloFacial Surgery, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK. hamadaho@aloola.sy
authors.forename: O
authors.initials: O
authors.lastname: Hamadah
authors.forename: P J
authors.initials: PJ
authors.lastname: Thomson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D054020:Lasers, Gas / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D018365:Neoplasm, Residual; D011230:Precancerous Conditions / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D012307:Risk Factors; D012959:Socioeconomic Factors; D015996:Survival Rate; D016896:Treatment Outcome