Background The objectives were to investigate the accuracy of sentinel lymph node (SLN) biopsy, detect the predictors for undetected or false-negative cases, evaluate the indications for SLN-navigated gastrectomy, and characterize the problems of SLN mapping in gastric cancer. The SLN concept may be applicable to early gastric cancer, particularly clinical T1N0M0 or T2N0M0 with tumor diameter ≤4 cm. Methods A total of 385 consecutive patients diagnosed with cT1N0M0 or cT2aN0M0 operable gastric cancer from April 1999 to December 2007 underwent radical gastrectomy with SLN mapping. SLNs were identified using radio-guided and dye-guided methods. Predictors for undetected or false-negative cases on SLN mapping were examined by multivariate regression analysis. Results The detection rate of hot and/or blue nodes was 96.6% (372 of 385). The accuracy of metastatic status based on SLNs was 98.9% (368 of 372) for all cases in whom SLNs could be detected. Furthermore, the accuracy of metastatic status based on SLNs was 99.1% (344 of 347) in cT1 gastric cancer and 96.0% (24 of 25) in cT2 gastric cancer. Pathologically, the tumors invaded to the muscularis propria or deeper in three of four false-negative cases. All but one case had metastatic lymph nodes within the sentinel basins. In terms of 5-y recurrence free survival, positive SLN cases (SLN(+)) had a worse prognosis than negative SLN cases (SLN(-); P = 0.008). Moreover, SLN(+) and non-SLN(-) cases (SLN(+)/non-SLN(-)) had a similar prognosis as SLN(+) and non-SLN(+) cases (SLN(+)/non-SLN(+)) (P = 0.511). On multivariate regression analysis, undetected or false-negative cases were significantly associated with the time period. Conclusions The present results appeared to validate the SLN concept for untreated cT1 gastric cancer with tumor diameter ≤4 cm. SLN mapping may provide an effective method of staging the lymph node status of patients undergoing minimized gastrectomy. Sentinel basin dissection guards against the possibility of leaving positive lymph nodes. Stabilization of the procedure and experience with SLN mapping in gastric cancer might decrease undetected or false-negative cases.
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