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

Abstract

Purpose: Photodynamic therapy (PDT) is used to treat Barrett's esophagus with high-grade dysplasia and mucosal carcinoma. Outcomes are variable with some patients having persistent disease, whereas others develop strictures. The aims of this study were (a) to compare porfimer sodium tissue uptake, light dose, and esophageal thickness with clinical outcomes and (b) to determine the selectivity of porfimer sodium uptake in diseased and normal epithelium. Experimental Design: Forty-eight hours after porfimer sodium infusion, patients underwent mucosal biopsy for quantification of the porfimer sodium. Laser light was delivered at 48 hours and again 24 or 48 hours later. Porfimer sodium was extracted from the biopsy samples and quantified using fluorescence spectroscopy. The enhanced photodynamic dose was determined as [porfimer sodium content * light dose/esophageal thickness]. PDT efficacy was determined 6 to 8 weeks later based on persistence or complete ablation of dysplasia or carcinoma. Results: Mean porfimer sodium content of 6.2 mg/kg (range, 2.6-11.2 mg/kg) and mean total light dose of 278 J/cm (range, 225-360 J/cm) resulted in a complete treatment. Mean porfimer sodium tissue content of 3.9 mg/kg (range, 2.1-8.1mg/kg) and mean total light dose of 268 J/cm (range, 250-350 J/cm) resulted in an incomplete treatment. The total esophageal thickness (range, 1.7-6.0 mm) and enhanced photodynamic dose were correlated with treatment outcome. Conclusions: Esophageal thickness is the strongest predictor of treatment outcome. The porfimer sodium content of Barrett's and normal tissue is not significantly different. ''Photodynamic dose'' for esophageal PDTshould incorporate the esophageal thickness.

Oncologic Photodynamic Therapy: Basic Principles, Current Clinical Status and Future Directions

“…A similar study supports this data by stating PDT proved effective in treating smaller BE or ADC lesions but complete ablation was less likely with lesions over 3 cm in length [ 153 ]. Maybe even more important than BE length is esophageal wall thickness, as thicker walls have a lower chance of achieving successful results with Photofrin ® -PDT [ 154 ].…”

Response Surface Methodology: An Extensive Potential to Optimize in vivo Photodynamic Therapy Conditions

“…In preliminary experiments, mice were treated under some of the strongest (i.e., with respect to the product of PS dose and light fluence, from the simplified formula of photodynamic dose [22]) conditions of the matrix (i.e., no. 6, 7, and 11).…”

Safety and feasibility of volumetric laser endomicroscopy in patients with Barrett’s esophagus (with videos)

“…Further, VLE provides high-resolution, 2-dimensional imaging information, which may be useful to characterize the thickness of BE mucosa to determine an optimal endoscopic treatment modality, such as the thinlayer radiofrequency ablation or deeper ablation with cryotherapy or photodynamic therapy. [35][36][37] The current multicenter, prospective study, performed in patients with known or suspected BE, has demonstrated that the Nvision VLE Imaging System effectively achieved completed scans (full 6-cm pullback that typically included the proximal stomach, gastroesophageal junction, and distal esophagus) in most cases (87%). These scans were performed during screening or surveillance upper endoscopy procedures and provided the physician with contemporaneous images of the distal esophageal mucosa and submucosa.…”