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Japanese Study Shows Endoscopic Dual Tracer Method for Sentinel Node Mapping in Gastric Cancer Is Safe and Accurate

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Key Points

  • The sentinel node detection rate using the dual tracer method was 97.5%.
  • The accuracy of determining metastatic status based on sentinel node evaluation was 99.0%.
  • No serious adverse effects related to endoscopic tracer injection or the sentinel node mapping procedure were observed.

In a study reported in Journal of Clinical Oncology, Yuko Kitagawa, MD, FACS, of Keio University School of Medicine, and colleagues found that sentinel node mapping using a standardized dual tracer endoscopic injection technique was safe and accurate in patients with gastric cancer.

Study Details

In this phase II multi-institutional trial, 397 patients with previously untreated cT1 or cT2 gastric adenocarcinomas < 4 cm in gross diameter underwent sentinel node mapping using a standardized dual tracer endoscopic injection technique involving injection of radiolabeled tin colloid and blue dye. Use of the radio-guided method alone was permitted in cases in which intraoperative injection of blue dye could not be performed. Following biopsy of the identified sentinel nodes, patients underwent comprehensive D2 or modified D2 gastrectomy according to current Japanese Gastric Cancer Association guidelines.

Sentinel Node and Metastasis Detection

The sentinel node detection rate using the dual tracer method was 97.5% (387 of 397 patients). Three (30%) of the 10 patients with undetected sentinel nodes had undergone radio-guided mapping alone. Lymph node metastasis was diagnosed in 57 (14.7%) of 387 patients, with the incidence of metastasis being significantly higher in cT2 tumors than in cT1 tumors (P < .001). Of the 57 patients with lymph node metastasis, 53 (93.0%) exhibited positive sentinel nodes. The accuracy of determining metastatic status based on sentinel node evaluation was 99.0% (383 of 387 patients). In 32 (60.4%) of 53 patients with positive sentinel nodes, lymph node metastasis was limited to sentinel nodes. Of 21 sentinel node–positive/nonsentinel node–positive patients, 15 (71.4%) had metastatic nonsentinel nodes within sentinel node basins, and six (28.6%) had metastatic nonsentinel nodes located outside the basins but within the extent of the D2 lymph node dissection. Four patients had false-negative sentinel node biopsy results, with three having either pT2 or primary tumors > 4 cm or both.

Safety

No serious allergic reactions were observed after tracer injection; cases of transient pigmentation and decreased pulse oximeter oxygen saturation, potentially related to intraoperative dye injection, were observed in 0.3% and 0.8% of patients, respectively. Use of the dual tracer method was not associated with a significant increase in the number of postoperative complications related to sentinel node biopsy procedures or standard surgery.

The investigators concluded: “The endoscopic dual tracer method for sentinel node biopsy was confirmed as safe and effective when applied to the superficial, relatively small gastric adenocarcinomas included in this study.”

The study was supported by grants from the Ministry of Health, Labour and Welfare of Japan and the Ministry of Education, Culture, Sports, Science, Technology, and Scientific Research of Japan.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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