Endoscopic photodynamic diagnosis: oral aminolevulinic acid is a marker ofGI cancer and dysplastic lesions

Background: Dysplasia and early cancer of the upper gastrointestinal (GI) t ract often are undetected at white-light endoscopy. We describe oral admini stration of 5-aminolevulinic acid for the in vivo photodynamic diagnosis of premalignant and malignant lesions during endoscopy. Methods: Four patients with known gastric adenoma (n = 1), macroscopically undetected but histologically proven esophageal squamous cell cancer (n = 1 ), suspected early cancer of the esophagus (n = I), and multiple duodenal a denomas (n = 1) were sensitized with 5-aminolevulinic acid administered ora lly (15 mg/kg body weight). Photodynamic diagnosis was conducted after a re tention time of 6 to 7 hours with a special light source capable of deliver ing either white or violet-blue light. Red fluorescence was detected throug h the gastroscope with an image-intensifying camera. Results: All malignant lesions exhibited red or bluish fluorescence during photodynamic diagnosis . Fluorescence-negative mucosal areas proved to be histologically benign. Conclusion: Fluorescence induced with 5-aminolevulinic acid might be useful for the endoscopic detection of dysplasia and early carcinoma in the upper GI tract. Further investigations are needed to evaluate the sensitivity an d specificity of photodynamic diagnosis for different tumor entities.