Next-generation laser-based photodynamic endoscopic diagnosis using 5-aminolevulinic acid for early gastric adenocarcinoma and gastric adenoma

Background: Photodynamic diagnosis (PDD) is an optical imaging technology based on the fundamental biological features of porphyrin metabolized in cancer cells. We reported the usefulness of laser-based photodynamic endoscopic diagnosis (LPDED) with 5-aminolevulinic acid (5-ALA) for early gastric cancers. However, the first-generation prototype endoscope system had the flaw that the images captured were rather dark. To overcome this, we constructed a next-generation endoscope system for LPDED.

Methods: We evaluated the usefulness of the next-generation prototype endoscope system, called Sie-P2, for brighter LPDED to detect early gastric cancer (EGC) and gastric adenoma. The 14 patients diagnosed with EGC and/or gastric adenoma who underwent endoscopic submucosal dissection (ESD) at our hospital between April 2018 and March 2019 were enrolled consecutively in this study. Patients were administered 5-ALA orally and LPDED was performed 3 h later. The primary endpoint was the presence of fluorescence in tumors when we performed LPDED. The secondary endpoint was to assess the adverse events related to each LPDED procedure.

Results: One patient was excluded because of a contraindication, while the remaining 13 patients (median 72 years, range 56-77; one female) with 16 lesions were assessed. There were 10 elevated lesions and 6 flat/depressed lesions; there were 10 EGCs and 6 adenomas. LPDED-fluorescence was detected in all 16 lesions (sensitivity 100%, 95% confidence interval 79-100%). Two cases showed temporary, though not substantial, elevation in blood liver function tests.

Conclusion: All lesions examined were LPDED-positive, indicating that the Sie-P2 system could be useful.