Peritoneal metastasis after operation for non-serosa-invasive gastric carcinoma and a prophylactic strategy for peritoneal dissemination

The established ultra-rapid quantitative RT-PCR system for intraoperative detection of intraperitoneal free cancer cells, the elucidated cause of peritoneal recurrence after curative operation for patients with non-serosa-invasive gastric cancer, and the extensive intraperitoneal lavage (EIPL) therapy for the prophylaxis of peritoneal recurrence from the results of evaluation using the ultra-rapid quantitative RT-PCR system were reviewed. We established ultra-rapid RT-PCR protocol that enables diagnosis of intraperitoneal cancer spread about 70 min, using LightCycler method in combination with automated mRNA extractor. Both the carcinoembryonic antigen (CEA) and cytokeratin (CK)20 messenger RNA (mRNA) in intraperitoneal lavages after lymph node dissection were identified in three (14.2%) and four (26.7%) patients with submucosal (SM) and muscularis propria (MP) tumors, respectively. Although peritoneal metastasis occurs in some patients with early gastric carcinoma, the reasons have not been fully established. These results clarified that peritoneal metastasis after operation for non-serosal-invasive gastric cancer was caused by opening lymphatic channels during lymph node dissection allowing the spread of viable cancer cells into the peritoneal cavity. Furthermore, EIPL method was performed in five cases with serosa-invasive (SE) gastric carcinoma, and its efficacy was evaluated by the quantitative RT-PCR. The quantitative RT-PCR demonstrated that EIPL reduced free cancer cells from 3.8×105±1.4×105 to 2.8±1.5 cells/100 ml of lavage by from six to eight washes, and they disappeared after the seventh to ninth wash. In conclusion, an ultra-rapid quantitative RT-PCR system for intraoperative detection of intraperitoneal free cancer cells was established for clinical use. It is suggested that the combination with the novel rapid detection system with the intraoperative therapy of EIPL can be a useful prophylactic strategy for peritoneal metastasis from gastric carcinoma. [Copyright &y& Elsevier]