Background: The aim of this study was to investigate the use of orally administered 5-aminolevulinic acid (ALA) for in vivo photodynamic diagnosis and follow-up of premalignant and malignant esophageal lesions.
Methods: Twenty-two patients with known or treated malignant and precancerous esophageal lesions were sensitized with orally administered ALA (15 mg/kg). Six patients had Barrett's esophagus, with or without severe dysplasia, 5 squamous cell cancer or early-stage (uT1N0M0) adenocarcinoma, 1 advanced-stage (uT3N1) adenocarcinoma, and 1 patient a lesion with an appearance that suggested esophageal cancer. Nine patients underwent photodynamic diagnosis for follow-up after treatment of esophageal cancer with curative intent; 6 had no macroscopically visible lesion and 3 a barely visible lesion under standard (white-light) endoscopy. Photodynamic diagnosis was conducted 6 to 7 hours after oral administration of ALA by using a special light source capable of delivering either white or violet-blue light. Red fluorescence was detected with a charged coupled device camera attached to a fiberoptic endoscope. Corresponding endoscopic, fluorescence, and microscopic findings were compared.
Results: By using histology as the reference standard (n = 86 biopsies), 85% of the biopsy sites with premalignant or malignant histopathology exhibited red fluorescence, whereas only 25% were detected with white-light endoscopy.
Conclusion: ALA-induced fluorescence might be useful for the early endoscopic detection of malignant esophageal lesions and follow-up after treatment of such lesions with curative intent.