Optimization of light dosimetry for photodynamic therapy of Barrett's esophagus: efficacy vs. incidence of stricture after treatment

Photodynamic therapy (PDT) may be used to ablate high-grade dysplasia/early stage cancer (HGD/T1) in patients with Barrett's esophagus. PDT may result in esophageal stricture. This nonrandomized, unblinded, dose de-escalation study in consecutive patients was designed to determine the lowest light dose effective for ablation of HGD/T1 while reducing the incidence of stricture. A total of 113 patients received an injection of porfimer sodium (2 mg/kg). Three days later, 630 nm light was delivered by using a 20-mm-diameter PDT balloon at doses of 115 J/cm (n = 59), 105 J/cm (n = 18), 95 J/cm (n = 17), or 85 J/cm (n = 19). Treatment efficacy was determined by obtaining biopsy specimens of the treated area 3 months later. The incidence of stricture was determined by the need for esophageal dilation to treat dysphagia. A stricture was considered severe if 6 or more dilations were required. The incidence of severe stricture was related to the light dose. At 115 J/cm, 15.3% of patients developed severe strictures compared with 5.3% to 5.6% of those treated with the lower doses. At a light dose of 115 J/cm, 17.0% of patients had residual HGD/T1. Light doses of 105 J/cm, 95 J/cm, and 85 J/cm resulted in residual HGD/T1 in 33.3%, 29.4%, and 31.6% of patients, respectively. None of the observations were statistically significant. Decreasing the light dose below 115 J/cm appeared to result in a reduced incidence rate of severe stricture but higher relative frequencies of residual HGD/T1 in Barrett's esophagus.