Feasibility of sentinel basin mapping after non-curative endoscopic resection for early gastric cancer: a prospective multicenter cohort study (SENORITA 2 trial).

[BACKGROUND] Standard treatment for non-curative endoscopic submucosal dissection (ESD) of early gastric cancer is radical gastrectomy with systematic lymph node dissection. However, the actual incidence of lymph node metastasis was reported to be 5-10%. The aim of this study is to evaluate the feasibility of sentinel basin mapping after non-curative ESD for early gastric cancer.

[METHODS] This is a multicenter, prospective feasibility study. Patients who underwent ESD for early gastric cancer and had a non-curative resection on final pathology were included. Sentinel basin mapping was performed using one of two methods: (1) endoscopic submucosal injection of a dual tracer, including a radioisotope and indocyanine green (ICG); or (2) fluorescence imaging after ICG injection. Following dissection of the identified sentinel basins, laparoscopic gastrectomy with D1 + lymphadenectomy was performed in all patients. The primary endpoint was the detection rate; secondary endpoints were sensitivity and postoperative complications.

[RESULTS] A total of 243 patients were enrolled from April 2017 to July 2024, and data from 238 eligible patients were analyzed. The dual tracer and fluorescence imaging with ICG were used in 216 and 22 patients, respectively. The overall detection rate was 97.1% (231/238), and metastatic lymph nodes were observed in 23 patients (9.7%, 23/238). The sensitivity was 69.6% (16/23) with 7 false-negative cases. Univariate analysis to identify risk factors for false-negative events showed that the early study period and institution had a nonsignificant trend. The postoperative complication rate was 10.1%, and the severe complication rate (Clavien-Dindo grade ≥ III) was 2.5%.

[CONCLUSION] Sentinel basin mapping after non-curative ESD achieved a high detection rate of 97.1%. However, the false-negative rate of 30.4% appears to be unacceptably high from an oncological safety perspective.