PHOTOSENSITIZATION AND PHOTODYNAMIC THERAPY OF ESOPHAGEAL, DUODENAL, AND COLORECTAL RUMORS USING 5-AMINOLEVULINIC ACID-INDUCED PROTOPORPHYRIN-IX - A PILOT-STUDY

The first study of photodynamic therapy in the human gastrointestinal tract using 5 aminolaevulinic acid (ALA) induced protoporphyrin IX as the photosensitising agent is described. Eighteen patients with colore ctal, duodenal, and oesophageal tumours were studied. After 30-60 mg/k g of ALA given orally, biopsy specimens of tumour and adjacent normal mucosa were taken 1-72 hours later. These specimens were examined by q uantitative fluorescence microscopy for assessment of sensitisation wi th protoporphyrin IX. Ten patients were given a second dose of ALA a f ew weeks later and their tumours were treated with red laser Light (62 8 nm). With 30 mg/kg ALA, the highest fluorescence values were detecte d in the duodenum and oesophagus, and the lowest in the large bowel. D oubling the ALA dose in patients with colorectal tumours gave protopor phyrin IX fluorescence intensities similar to those in patients with u pper gastrointestinal lesions and improved the tumour:normal mucosa pr otoporphyrin IX sensitisation ratio. The treated patients showed super ficial mucosal necrosis in the areas exposed to laser light. Six had t ransient rises patients aspartate aminotransferases, skin photosensiti vity reactions, and five mild nausea and vomiting. In conclusion, phot odynamic therapy with systemically administered ALA may be a promising technique for the treatment of small tumours and areas of dysplasia s uch as in Barrett's oesophagus.