Staging laparoscopy using ALA‐mediated photodynamic diagnosis improves the detection of peritoneal metastases in advanced gastric cancer

Abstract Background This study evaluated the usefulness of photodynamic diagnosis (PDD) using oral 5‐aminolevulinic acid (ALA) for the detection of peritoneal metastases in advanced gastric cancer. Method First, the numbers of peritoneal metastatic nodules that were visible under conventional white light (WL) and ALA‐induced fluorescence (ALA‐F) were quantified in a mouse model of peritoneal metastasis to compare the tumor detection rate. Next, staging laparoscopy (SL) using ALA‐PDD was performed in 13 advanced gastric cancer patients with serosa‐invading tumors, and the detection sensitivity of ALA‐PDD was compared to the observations using WL. Results The tumor detection rate using ALA‐F was significantly higher than the detection rate using WL (72% vs. 39%, respectively, P < 0.0001). Peritoneal metastases were detected in five patients using SL with ALA‐PDD, and liver metastases were detected in one patient. These metastases were confirmed using histological examination. Three metastatic lesions that were invisible under WL were detected under ALA‐F. Conclusion This study demonstrated that SL with ALA‐PDD improved the detection sensitivity for peritoneal metastases. ALA‐PDD may be an important technique for the preoperative staging of advanced gastric cancer, and ALA‐PDD will provide useful information for the selection of therapeutic modality. J. Surg. Oncol. 2012; 106:294–298. © 2012 Wiley Periodicals, Inc.