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.

Pilot Study on Light Dosimetry Variables for Photodynamic Therapy of Barrett's Esophagus with High-Grade Dysplasia

“…Panjehpour et al (10) and van Veen et al (11) measured the actual light fluence at the mucosal surface and found that it was 1.5 to 3.9 times higher than expected. Mackenzie et al (12) reported that esophageal 5-aminolaevulinic acid-PDT treatment success was correlated to the administered PDT light dose. However, Panjehpour et al (13) investigated the effect of light dose on PDT-induced stricture formation and found that each of the light doses (85-115 J/cm) led to a range of treatment outcomes from residual disease to stricture formation, giving evidence that the incident light dose is only one factor in treatment outcome.…”

ALA PDT for high grade dysplasia in Barrett's oesophagus: review of a decade's experience

“…17,18 It is of historical interest that comparable studies were not performed for porfimer sodium until recently, in an attempt to reduce the incidence of oesophageal strictures. 19 At the start of these studies, all patients were given ALA as a single dose of 30mg/kg dissolved in water, 4 hours before light delivery.…”

Endoscopic Therapy of Neoplasia Related to Barrett's Esophagus and Endoscopic Palliation of Esophageal Cancer

“…Another is the systemic distribution of the photosensitizing agents that requires patients to avoid direct sunlight and wear full protective clothing (eg, sunglasses, widebrim hats, long-sleeved shirts) for several weeks to prevent sunburn, which could be signifi cant. 71,72 Also, patients can develop esophageal strictures following prior ablative treatments. Overholt et al 70 reported cases of adenocarcinoma that arose from buried Barrett's glands following PDT.…”