[Reasonable extent of No.12a lymph node dissection in laparoscopic surgery for locally advanced distal gastric...

Objective: To explore the appropriate extent of No.12a lymph node dissection in locally advanced distal gastric cancer patients. Methods: This study utilized a prospective observational research design, The inclusion criteria were: (1) age 18-75 years, and Eastern Cooperative Oncology Group score ≤2; (2) histologically confirmed gastric adenocarcinoma, and tumor extending from the lower-middle of the gastric body to the antrum; (3) underwent totally laparoscopic or laparoscopy-assisted distal gastrectomy with D2 lymphadenectomy; (4) postoperative pathological examination confirmed stage pT2-4aNxM0 with negative margin; (5) intraoperative separate pathological examination of No.12a lymph nodes; (6) complete clinicopathological and follow-up data. Exclusion criteria were: (1) Multiple malignant lesions in the stomach; (2) previous upper abdominal surgery (except laparoscopic cholecystectomy); (3) history of intestinal obstruction; (4) combined organ resection; (5) invasion of the superior part of duodenum. A prospective single-center study enrolled 191 local advanced distal gastric cancer patients who underwent laparoscopic radical distal gastrectomy at Tianjin Medical University Cancer Institute & Hospital from January 2023 to April 2025. The No. 12a lymph nodes were categorized into two groups: No. 12a1 (lymph nodes located on the anterior and left wall surfaces of the proper hepatic artery) and No. 12a2 (lymph nodes located between the proper hepatic artery and the portal vein, and along the left wall of the portal vein). The lymph node metastasis rate of different groups was recorded. The relationship between No.12a lymph node metastasis and clinicopathological features, regional lymph node metastasis was analyzed. Results: A total of 191 patients were included, with 139 males (72.8%) and 52 females (27.2%), with median age of 61 years. A total of 7536 lymph nodes were dissected with a median of 37 (range: 17-89) nodes per case, including 1046 metastatic lymph nodes (median: 3, range: 0-40).The No.12a lymph node metastasis rate was 7.9% (15/191). The No.12a1 lymph node metastasis rate was 6.8% (13/191), and the metastasis rate of No.12a2 lymph node was 3.7% (7/191). Correlation analysis indicated that No.12a2 lymph node metastasis was correlated with pN3 (χ²=6.217,P=0.013) and pathological stageⅢ(χ²=6.475, P=0.011). The regional lymph nodes (No.6, No.7, No.8a, No.9, and No.12a1) metastasis was significant associated with No.12a2 lymph node metastasis (all P<0.05). Multivariate analysis indicated that only No.12a1 lymph node metastasis was an independent risk factor of No.12a2 lymph node metastasis. Conclusions: The metastasis rate of No.12a2 lymph node was relatively low in locally advanced distal gastric cancer, the clinical value of No.12a2 lymph node dissection needs further investigation. For patients with clinical stage cN3 or clinical stage III, as well as No.12a1 group of lymph node metastasis was detected during operation, systematic dissection of No.12a2 group lymph node may be more meaningful.