Sentinel node mapping for gastric cancer: is the jury still out?

Abstract

limited to within the sentinel basins in cT1N0 gastric cancer. Sentinel basins are therefore good targets of selective lymphadenectomy for cT1N0 gastric cancer in patients who are at potential risk of micrometastasis [6]. Furthermore, laparoscopic local resection is theoretically feasible for curative treatment of SN-negative early gastric cancer [7]. In Japan, clinical applications of this novel, minimally invasive approach have had great impact on patient care for gastric cancer because more than half of gastric cancer cases treated in major institutions belong to this category. Since 2000, several reports of single institutional experiences emphasizing the validity and clinical usefulness of SN mapping for gastric cancer have been published [5–11]. However, the introduction of this technology into actual standard patient care for gastric cancer requires considerable caution, because there is a potential risk of negatively affecting long-term survival due to false negative SN status results. In this issue of Gastric Cancer, Isozaki and colleagues present the results of the first multicenter clinical trial of SN mapping for gastric cancer using a dye-guided method [12]. Although the patient population enrolled in the study is limited, several important messages can be obtained. This study was designed to investigate the feasibility of SN mapping for gastric cancer, using the dye-guided method as a simple method that can be conducted even in community hospitals without any special equipment. Although the false negative rates reported in the study (29% in all T1, 44% in all T2) were disappointing with regard to future clinical applications to change patient care for gastric cancer, the data of this study must be interpreted very carefully. The most serious limitation of the study was the inclusion criteria of participating institutions in terms of previous experience with SN mapping for gastric cancer. In the field of breast cancer surgery, the significance of the technical learning curve has already been clearly demonstrated [13]. Cox et al., reporting on breast cancer, suggested The huge achievements of gastric surgeons in the last century in establishing radical surgery with extensive lymph node dissection for gastric cancer deserve unequivocal respect. Now we have to proceed to the next stage in the twenty-first century by improving postoperative function and quality of life after gastric cancer surgery without impairing long-term outcome. In this respect, the sentinel node (SN) concept may provide a breakthrough as a novel diagnostic tool. The first possible sites of metastasis along the route of lymphatic drainage from the primary lesion are known as SNs, and these are detectable using injection of dyes or radioactive tracers. After Morton et al. demonstrated the concept of SN initially in a feline model and later in a clinical study involving patients with malignant melanoma [1], the clinical impact of the SN concept in surgical oncology for various solid tumors has been a vigorously debated topic. Although we have to wait to see the results of ongoing multicenter prospective randomized control trials for SN biopsy, less invasive, modified surgical approaches are already being employed in breast cancer and melanoma. The applications of the SN concept for gastrointestinal (GI) malignancies were not recognized until the late 1990s because of the multidirectional and complicated lymphatic flow from the GI tract. However, the past 5 years have seen the recognition of several studies supporting the validity of the SN concept for GI cancers [2–5]. Despite the multidirectional and complicated lymphatic flow from gastric mucosa, the anatomical situation of the stomach is relatively suitable for SN mapping in comparison with organs such as the esophagus and rectum, embedded in enclosed spaces. In particular, clinically T1N0 gastric cancer seems to offer opportunities to modify the therapeutic approach. From the data reported in the literature, micrometastasis tend to be