胃癌におけるレーザー光を用いた光線力学的内視鏡診断(PDD: Photodynamic diagnosis)

This review focuses on the studies to investigate the feasibility of 5-aminolevulinic acid （5-ALA）-mediated photodynamic diagnosis（PDD） in particular, for detecting gastric cancer and upper GI tumors in the earlier stage. Using a prototype endoscope equipped with a blue laser light excitation for protoporphyrin IX, a photosensitizer, 5-ALA-mediated PDD was conducted in 30 cases of gastric cancer and upper GI tumors. 5-ALA solution was given orally 3 hours before PDD. Red fluorescence signal and intensity was assessed as for clinicopathological features of the cases. The laser-based endoscopy could detect upper GI tumors as red fluorescent navigation （PDD-positive） in 77%（23/30）．There were nominal adverse events. Thus, 5-ALA-PDD using the blue laser-equipped endoscope offers a promising diagnostic tool for the other digestive tumors such as colonic and pancreatic tumors. Further studies on the basic mechanisms of the difference in fluorescence intensity are warrant to be executive.