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.
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 cancerpatients 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.