SENSITIZATION AND PHOTODYNAMIC THERAPY (PDT) OF GASTROINTESTINAL TUMORS WITH 5-AMINOLEVULINIC ACID (ALA) INDUCED PROTOPORPHYRIN-IX (PPIX) -A PILOT-STUDY

5-Aminolaevulinic acid (ALA) is a promising agent for photodynamic the rapy (PDT) sensitization as it can be given orally and only causes ski n photosensitivity for 1-2 days. In fluorescence and photodynamic stud ies 26 patients with benign and malignant gastrointestinal tumors were given 30-60 mg ALA orally (single or divided doses) and biopsies were taken of tumor and normal tissue at 1-24 hours for fluorescence micro scopy. With 30 mg/kg, highest protoporphyrin IX (PPIX) levels were see n in esophagus, duodenum and less in colon, but without tumor selectiv ity. Better tumor selectivity was seen in colon after 60 mg/kg (5:1). Six patients had transient rises in transaminases and five mild nausea . Sixteen patients were later treated (after further ALA) with red lig ht (628 nm, bare or diffuser fibre, 50-100 J at 50 mW at each site). A ll but two showed subsequent necrosis, but only 0.5-1.5 mm of depth. P DT with ALA is simple, safe and promising for tumors in the gastrointe stinal tract. Modification of treatment parameters may make it suitabl e for larger lesions.