Photodynamic diagnosis (PDD) is an imaging technology that is based on the fundamental biological features of cancer cells. Five-aminolevulinic acid (ALA), a precursor of photosensitizing protoporphyrin IX (PpIX) has been applied. In fact, ALA-mediated PDD provides good visualization for certain tumors. However, there have been few studies on clinical application of PDD for gastrointestinal (GI) cancers. This study was aimed to investigate the feasibility of ALA-mediated PDD for navigation of upper GI tumors. Materials and methods: Using a newly developed endoscope equipped with a blue laser light excitation, ALA-mediated PDD was conducted in 27 lesions from 23 patients with upper GI tumors including 2 Barrett's intramucosal cancers. ALA solution was given orally 3. h before PDD. All the adenocarcinomas came under clinical stage I, and the tumors were resected endoscopic submucosal dissection and/or laparoscopic surgery. Red fluorescence signal and intensity was assessed as for clinicopathological features of the cases. Results: The laser-based endoscopy could detect upper GI tumors as red fluorescent navigation (PDD-positive) in 23 of the 27 lesions. All but one intestinal typed tumors in histopathology were significantly PDD-positive, whereas each signet ring cell carcinoma was PDD-negative. There was a significant difference in tumor size between the PDD-positive and -negative tumors. The elevated lesions emitted significantly more intense fluorescence. Conclusions: Fluorescence navigation by ALA-mediated PDD provided sufficient detection of upper GI tumors in particular for the intestinal typed tumors. Thus, ALA-PDD using the blue laser-equipped endoscope offers a promising diagnostic tool.
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