Novel Biomedical Imaging Approach for Detection of Sentinel Nodes in an Orthotopic Xenograft Rat Model of Human Gastric Carcinoma

With advances in endoscopic techniques and the widespread use, detection rates for early gastric carcinoma are increasing, and minimally invasive surgery becomes more important in the treatment. Minimally invasive surgery with less extensive dissection involves avoidance of unnecessary lymphadenectomy, leading to the reduction of postoperative morbidity and mortality rates and the improvement of postoperative quality of life without impairing recurrence-free survival. Sentinel node (SN) biopsy is useful to dissect lymph node (LN) rationally and to avoid unnecessarily extensive lymphadenectomy in surgery for gastric carcinoma, as has been established in breast cancer and melanoma (Krag et al., 1998; Morton, 1992; van der Veen et al., 1994; Veronesi et al., 1997). Thus, SN biopsy could be a promising method for the management of gastric carcinoma. The concept is based on the notion that SNs are the first lymph nodes to which cancer cells metastasize from the primary lesion (Sobin, 2003). The presence of tumor cells in SNs indicates that cancer cells may metastasize to downstream nodes. Conversely, the absence of metastatic tumor cells in SNs indicates that metastasis is unlikely in other nodes. However, a convenient and sensitive method useful for the detection of SNs of gastric carcinoma has not been standardized. Development of a convenient and sensitive method useful for the detection of SNs will enable surgeons to rationally determine the extent of LN dissection and to perform minimally invasive surgery (Krag et al., 1998; Morton, 1992; van der Veen et al., 1994; Veronesi et al., 1997). Several methods have been developed to detect SNs using radioactive materials or vital dyes, such as patent blue violet, isosulfan blue and indocyanine green in gastric carcinoma (Hayashi et al., 2003; Hiratsuka et al., 2001; Hundley et al., 2002; Ichikura et al., 2002; Isozaki et al., 2004; Karube et al., 2004; Kim, M.C. et al., 2004; Kitagawa & Kitajima, 2002; Lee et al., 2005; Miwa et al., 2003; Nimura et al., 2004; Osaka et al., 2004; Ryu et al., 2003; Simsa et al., 2003; Song et al., 2004; Tanaka et al., 2004). Although the sensitivity of these materials or dyes for the detection of SNs is high, sentinel node navigation surgery using dyeor radio-guided methods has not yet been widely performed in early gastric cancer, partly owing to false-negative results in detecting SNs with tumor cell metastases, or