Refining gastric cancer staging: examining the interplay between number and anatomical location of metastatic lymph nodes - a retrospective multi-institutional study.

BACKGROUND: The current gastric cancer staging system relies on the number of metastatic lymph nodes (MLNs) for nodal stage determination. However, incorporating additional information such as topographic status may help address uncertainties. This study evaluated the appropriateness of the current staging system and relative significance of MLNs based on their anatomical location. METHODS: Patients who underwent curative gastrectomy for gastric cancer between 2000 and 2019 at six Catholic Medical Center-affiliated hospitals were included. Lymph node-positive patients were classified into the perigastric (stations 1-6, group P) or extragastric (stations 7-12) groups. The extragastric group was further subdivided into the near-extragastric (stations 7-9, group NE) and far-extragastric (stations 10-12, group FE) groups. RESULTS: We analyzed the data of 3,591 patients with positive lymph node metastases. No significant survival differences were found between group P and the extragastric group in each N stage. However, in N1 and N2, group FE showed significantly worse survival than the other groups (p = 0.013 for N1, p < 0.001 for N2), but not in N3. In the subgroup analysis, group FE had a significantly lower overall survival in N2, regardless of the cancer location. CONCLUSIONS: Our large-scale multi-institutional big data analysis confirmed the superiority of the current numerical nodal staging system for gastric cancer. Nonetheless, in N1 and N2 in which there is an upper limit on metastatic nodes, attention should be paid to the potential significance of topographic information for specific nodal stations.

Is Total Omentectomy Mandatory in T3 and T4a Gastric Cancer for Laparoscopic Distal Gastrectomy?

BACKGROUND: Despite the lack of strong evidence, total omentectomy (TO) remains the recommended procedure for gastric cancer (GC) for T3 or deeper tumors. Partial omentectomy (PO) has recently become a preferred procedure owing to its simplicity during laparoscopic distal gastrectomy (LDG); however, the oncological role of PO needs to be elucidated. METHODS: Overall, 341 patients with T3 or T4a GC who had undergone LDG between 2009 and 2016 were divided into TO (n = 167) and PO (n = 174) groups. Propensity matching was performed with respect to covariance age, sex, T and N stage, tumor size, and degree of tumor differentiation. Clinicopathological characteristics and long-term follow-up data were analyzed for both groups. RESULTS: After successful propensity matching, both groups included 107 patients. In a matched cohort, no significant difference in clinicopathologic features and short-term surgical outcomes was observed between the two groups. Furthermore, no significant difference in relapse-free survival (RFS; p = 0.201) and peritoneal seeding-free survival (PSFS; p = 0.094) was observed. However, tumor recurrence as peritoneal metastasis occurred in 5 (4.7%) patients in the PO group and 13 (12.1%) patients in the TO group. In Cox proportional hazards analysis, omentectomy was not identified as a significant factor for RFS, PSFS, and overall survival; however, advanced N and T4a stage were considered significant factors for RFS and PSFS, respectively. CONCLUSIONS: PO may be adopted during the LDG of T3 or T4a GC without definite gross serosal exposure. More large-scale evidence or prospective study is recommended.