Photodynamic Diagnosis of Peritoneal Dissemination of Colorectal Cancer Using 5-Aminolevulinic Acid during Laparoscopic Surgery

Background: Photodynamic diagnosis (PDD) using 5-aminolevulinic acid (5-ALA) is useful for detecting microperitoneal dissemination in gastric cancer. However, reports on its use in colorectal cancer are sparse. In this study, we performed PDD with 5-ALA to diagnose peritoneal dissemination in colorectal cancer during laparoscopic surgery.Methods: Between January 2018 and March 2019, we examined six patients scheduled laparoscopic surgery for colorectal cancer (cT3 or deeper) with suspected peritoneal dissemination. A solution of 5-ALA (20 mg/kg) in water was orally administered 3 to 4 hours before surgery. Intraoperatively, the peritoneal cavity was observed with white and fluorescent lights. Nodules suspected as dissemination lesions were resected and the presence or absence of seeding was confirmed histopathologically.Results: The median time from oral 5-ALA administration to observation was 226 minutes. Peritoneal nodules found in four of six cases using white light were collected. In Case 5, white nodules were observed in white light and luminescence in fluorescent light. Of the nodules collected, only that of Case 5 was pathologically diagnosed as disseminating. No adverse events were observed.Conclusions: We attempted PDD using 5-ALA during laparoscopic surgery for colorectal cancer. Observing more cases and optimizing observation conditions are required to improve accuracy.This study was registered at the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN Exam ID: UMIN000030531).