OBJECTIVETo investigate the feasibility and accuracy of detection of sentinel lymph nodes (SLN) with combining the dye-directed and radioguided methods in gastric cancer and assess its potential role in determining the rational extent of lymphadenectomy in gastric cancer surgery.

METHODSTwenty-six patients of gastric cancer diagnosed as T(1)-T(3) were enrolled in this study. Endoscopic injection submucosally of (99m)Tc labeled sulfur colloid solution was performed around the primary tumor 2 - 4 h before operation. Immediately after laparotomy, patent blue violet was injected into subserosal layer adjacent to the tumor. SLNs were defined as blue stained nodes or(and) those containing 10 times more radioactivity than surrounding tissue with a gamma probe. Standard radical gastrectomy with lymphadenectomy (D(2) or D(3)) was performed in most of the patients, however, limited surgery was performed in early gastric cancer (EGC) when a rapid frozen examination indicated negative SLNs. All resected nodes were examined postoperatively by routine HE stain and those negative SLNs were examined with further cytokeratin immunohistochemistical staining. The diagnostic accuracy, sensitivity, negative predictive value and false-negative rate of regional lymph node status on the basis of SLN status were calculated respectively.

RESULTSSLNs were dectected in 25 of 26 patients with a successful detection rate of 96%. The number of SLNs ranged from 1 to 6, with a mean value of 3.2 per case. The SLNs of gastric cancer were only found in N(1) area in 50% of the cases, and only in N(2) or N(3) in 12%. The incidence of metastasis was significantly higher in SLNs than in non-SLNs (35% vs 7%). The diagnostic accuracy, sensitivity, negative predictive value and false-negative rate were 96%, 94%, 7/8 and 6% respectively. Complete analysis of SLN upstaged 2/7 of patients of gastric cancer.

CONCLUSIONSThe SLN concept is validated in gastric cancer. Combined-agent SLN mapping is an accurate diagnostic procedure for detecting lymph node metastasis in patients with gastric cancer and may indicate rational extent of lymphadenectomy for gastric cancer.