title: Nitrous oxide cryotherapy for primary periocular basal cell carcinoma: outcome at 5 years follow-up.
abstract: OBJECTIVE
  To report the outcome at 5-year follow-up of a defined series of patients with primary periocular basal cell carcinoma treated by cryotherapy using a nitrous oxide probe.
  
  
  METHODS
  A prospective, non-comparative, interventional case series. One hundred primary periocular basal cell carcinomas were treated with a double freeze-thaw cycle nitrous oxide contact cryotherapy probe. Inclusion criteria were clinically well-defined primary periocular basal cell carcinomas with maximum diameter of 8 mm. The main outcome measure was histologically proven recurrence rate at 5-year follow-up.
  
  
  RESULTS
  Kaplan-Meier survival analysis showed a 5-year recurrence rate of 8%. Cox regression analysis revealed no correlation between tumour site, tumour size, cryotherapy freeze time and recurrence (p=0.60, p=0.86 and p=0.71, respectively). Thirty-six per cent of patients were lost to follow-up at 5 years following treatment.
  
  
  CONCLUSIONS
  The results of this series suggest that nitrous oxide probe cryotherapy for primary periocular basal cell carcinomas up to 8 mm diameter has a recurrence rate of ∼8%. Cryotherapy has certain advantages over surgical removal of tumours of this size in the periocular region, but careful follow-up is advisable.
authors.affiliation: Moorfields Eye Hospital, London, UK.
authors.forename: I
authors.initials: I
authors.lastname: Moesen
authors.forename: M
authors.initials: M
authors.lastname: Duncan
authors.forename: C
authors.initials: C
authors.lastname: Cates
authors.forename: A
authors.initials: A
authors.lastname: Taylor
authors.forename: R V
authors.initials: RV
authors.lastname: Wintle
authors.forename: A
authors.initials: A
authors.lastname: Ismail
authors.forename: D Khan
authors.initials: DK
authors.lastname: Lim
authors.forename: A G
authors.initials: AG
authors.lastname: Tyers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002280:Basal Cell Carcinoma / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D017679:Cryotherapy / Q000295:instrumentation / Q000379:methods*; D005142:Eyelid Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D009609:Nitrous Oxide / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D009609:Nitrous Oxide