[Clinical study on lymph node metastasis regularity in 1456 patients with gastric cancer]

To investigated the characteristics and regularity of lymph node metastasis around gastric cancer in order to provide reference for standardized and optimal surgical treatment.

A retrospective case series study was carried out on 1456 patients with gastric cancer undergoing surgical treatment at the Affiliated Tumor Hospital of Tianjin Medical University from March 2003 to August 2011. The number of harvested lymph node and metastasis status of various lymph node station were determined by routine pathological examination of specimens, including resected gastric tissue and dissected lymph node tissue, according to the 13th version of the Japanese Gastric Cancer Treatment Guidelines. Tumor T, N and M staging was performed to evaluate lymphatic metastasis status of different locations of gastric cancer according to the TNM staging criteria of the 8th edition of the American Joint Committee on Cancer (AJCC). The influence of gender, age, tumor diameter, Borrmann type, T staging and M staging, tumor differentiation degree, invasion of vessels, lymphatic vessels and nerves, radical surgical degree and other clinical factors on lymph node metastasis was analyzed.

A total of 1062 cases(72.9%) had lymph node metastasis in the 1456 patients with gastric cancer. A total of 9766 lymph nodes were positive for metastasis. Lymph node metastasis occurred in 11 of 44 (25.0%) patients with early gastric cancer and in 1051 of 1412 (74.4%) patients with advanced gastric cancer. The largest number of lymph node metastases was found in No.3 station [653 cases (44.8%)], followed by No.6 [437 cases(30.0%)], No.7 [345 cases (23.7%)], No.1 [304 cases (20.9%)], No.4sb [290 cases (19.9%)]. No.14v lymph node metastasis was observed in 23 cases, of whom No.6 (16 cases, 69.6%), No.8a (15 cases, 65.2%) and No.3 (12 cases, 52.2%) developed simultaneous metastasis. As for different locations of gastric cancer, stations with more lymph node metastasis in 309 patients with proximal gastric cancer were No.3 (133 cases, 43.0%), No.1 (96 cases, 31.1%), No.2 (90 cases, 29.1%) and No.7 (89 cases, 28.8%); in 144 patients with middle gastric cancer were No.3 (68 cases, 47.2%), No.6 (50 cases, 34.7%), No.7 (40 cases, 27.8%) and No.4sb (38 cases, 26.4%); in 700 patients with distal gastric cancer were No.3(287 cases, 41.0%), No.6 (265 cases, 37.8%), No.4sb (138 cases, 19.7%) and No.8a (138 cases, 19.7%); in 303 cases with diffuse-type gastric cancer were No.3 (165 cases, 54.4%), No.6 (100 cases, 33.0%), No.7 (88 cases, 29.0%), No.1 (84 cases, 27.7%) and No.4sb (72 cases, 23.8%). The incidence of lymph node skip metastasis was 7.2% (105/1456) in whole group. Positive lymph node metastasis was associated with tumor size (RR=2.016, 95%CI: 1.550-2.621, P=0.000), tumor differentiation(RR=1.631, 95%CI:1.405-1.894, P=0.000), tumor T staging (RR=1.886, 95%CI: 1.629-2.184, P=0.000), tumor M staging (RR=3.671, 95%CI:1.265-10.660, P=0.017) and radical surgery(RR=3.819, 95%CI: 2.023-7.207, P=0.000).

The main direction of peripheral lymph node drainage in gastric cancer is lesser curvature, and then the left gastric artery, the common hepatic artery and the peripheral lymph nodes of the celiac axis, and finally the peripheral lymph nodes of the abdominal aorta. Therefore the No.6 station lymph node adjacent to the perigastric area, the No.7, No.8 and No.9 lymph nodes should be the focus of the radical surgical dissection of gastric cancer. Tumor size, differentiation degree, invasion depth and distant metastasis have significant association with lymph node metastasis. For patients with adverse factors, radical surgery is necessary to ensure efficacy.