title: How light dosimetry influences the efficacy of photodynamic therapy with 5-aminolaevulinic acid for ablation of high-grade dysplasia in Barrett's esophagus.
abstract: Photodynamic therapy (PDT) with 5-aminolaevulinic acid (ALA) is a novel treatment for high-grade dysplasia (HGD) in Barrett's esophagus (BE). Our aim was to evaluate the effectiveness of differing light doses. Patients with HGD in BE received oral ALA (60 mg/kg) activated by low (500 J/cm), medium (750 J/cm), high (1,000 J/cm), or highest (1,000 J/cm x2) light dose at 635 nm. Follow-up was by regular endoscopy with quadrantic biopsies. Twenty-four patients were treated. Successful eradication of HGD was significantly correlated with light dose (log rank, p < 0.01). Six of eight patients (75%) treated with the highest light dose, one of two treated with high dose (50%), two of nine (22%) receiving medium light dose, and zero of five receiving low light dose had successful eradication of HGD (median follow-up 45 months, range 1-78 months). No skin photosensitivity or esophageal strictures occurred. The efficacy of ALA-PDT for eradication of HGD in BE is closely related to the light dose used. With a drug dose of 60 mg/kg and light at 635 nm, we recommend a minimum light dose of 1,000 J/cm of esophagus. This dose appears safe.
authors.affiliation: National Medical Laser Centre, Department of Surgery, Royal Free and University College Medical School, University College London, UK.
authors.forename: Gary D
authors.initials: GD
authors.lastname: Mackenzie
authors.forename: Neil F
authors.initials: NF
authors.lastname: Jamieson
authors.forename: Marco R
authors.initials: MR
authors.lastname: Novelli
authors.forename: C Alexander
authors.initials: CA
authors.lastname: Mosse
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Clark
authors.forename: Sally M
authors.initials: SM
authors.lastname: Thorpe
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Bown
authors.forename: Laurence B
authors.initials: LB
authors.lastname: Lovat
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D001471:Barrett Esophagus / Q000473:pathology / Q000628:therapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D008027:Light; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000295:instrumentation / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid