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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Panjehpour
Masoud
M
Center of Excellence for Photodynamic, Therapy of Barret's Esophagus, Thompson Cancer Survival Center, Knoxville, TN 97916, USA.
Overholt
Bergein F
BF
Phan
Mary N
MN
Haydek
John M
JM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001471:Barrett Esophagus / Q000188:drug therapy* / Q000473:pathology; D017323:Dihematoporphyrin Ether / Q000627:therapeutic use*; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D004940:Esophageal Stenosis / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D005500:Follow-Up Studies; D006414:Hematoporphyrin Photoradiation / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012062:Relative Biological Effectiveness; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D017323:Dihematoporphyrin Ether