What is the problem in clinical application of sentinel node concept to gastric cancer surgery?

Abstract

More than ten years have passed since the sentinel node (SN) concept for gastric cancer surgery was first discussed. Less invasive modified surgical approaches based on the SN concept have already been put into practice for malignant melanoma and breast cancer, however the SN concept is not yet placed in a standard position in gastric cancer surgery even after two multi-institutional prospective clinical trials, the Japan Clinical Oncology Group trial (JCOG0302) and the Japanese Society for Sentinel Node Navigation Surgery (SNNS) trial. What is the problem in the clinical application of the SN concept to gastric cancer surgery? There is no doubt that we need reliable indicator(s) to determine with certainty the absence of metastasis in the lymph nodes in order to avoid unnecessary lymphadenectomy. There are several matters of debate in performing the actual procedure, such as the type of tracer, the site of injection, how to detect and harvest, how to detect metastases of SNs, and learning period. These issues have to be addressed further to establish the most suitable procedure. Novel technologies such as indocyanine green (ICG) fluorescence imaging and one-step nucleic acid amplification (OSNA) may overcome the current difficulties. Once we know what the problems are and how to tackle them, we can pursue the goal.

Keywords: Clinical trial; Gastric cancer; Indocyanine green fluorescence imaging; One-step nucleic acid amplification; Sentinel node.

Fig. 1

Trial scheme of the JCOG0302. Intraoperative detection of metastases in one plane of largest dimension of green nodes as SNs was performed using frozen sections and hematoxylin-eosin staining. Gastrectomy with lymphadenectomy was performed after SN biopsy. JCOG0302 = Japan Clinical Oncology Group trial; ICG = indocyanine green; SN = sentinel node.

Fig. 2

ICG-based novel techniques. Infrared imaging (B) allows easy visualization of the LNs, which are otherwise hardly recognized by ICG green color alone (A). The ICG fluorescence imaging (C) also allows separate visualization of LNs. Quotation from reference number 18 cited with minor alteration. ICG = indocyanine green; LN = lymph node.