Endoscopic photodynamic diagnosis: oral aminolevulinic acid is a marker of GI cancer and dysplastic lesions.

BACKGROUND: Dysplasia and early cancer of the upper gastrointestinal (GI) tract often are undetected at white-light endoscopy. We describe oral administration 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 = 1), and multiple duodenal adenomas (n = 1) were sensitized with 5-aminolevulinic acid administered orally (15 mg/kg body weight). Photodynamic diagnosis was conducted after a retention time of 6 to 7 hours with a special light source capable of delivering either white or violet-blue light. Red fluorescence was detected through 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 and specificity of photodynamic diagnosis for different tumor entities.