New Light on Barrett’s Esophagus

The incidence of esophageal carcinoma has been steadily increasing in many western countries in the last 30 years. A current hypothesis is that the majority of the adenocarcinomas arise in Barrett’s esophagus (BE), following a sequence of metaplasia through dysplasia to carcinoma. When BE progresses to high grade dysplasia or adenocarcinoma, esophageal resection is the treatment of choice in patients fit for surgery. However, most patients with esophageal adenocarcinoma have not been recognized with BE previously, and the majority of patients with BE will not develop esophageal adenocarcinoma. Therefore less invasive endoscopic therapy has been used for treatment of BE with dysplasia for patients unfit for surgery. Also, endoscopic therapy has been used as preventive strategy for development of esophageal cancer by ablation of the premalignant Barrett’s epithelium. Photodynamic therapy (PDT) with use of 5-aminolevulinic acid (ALA) is a relatively new treatment option ideally leading to endoscopic ablation of the Barrett’s mucosa. At present, results of clinical ALA-PDT are suboptimal. Removal of dysplasia has been successful, but residual BE remains. In order to optimize ALA-PDT for treatment of BE, more accurate light dosimetry and monitoring of PpIX fluorescence decay may be valuable tools. Light dosimetry, standardized for all patients in vivo and adjusted to tissue optical properties, may improve outcome of ALA-PDT. With PpIX fluorescence monitoring, ALA-PDT can be monitored during treatment. In this thesis, these parameters have been studied using the rat as experimental model.