Objective: The purpose of this study is to analyze the relationship between the number of examined lymph nodes (NexLN) and survival in gastric cancer and to determine whether the metastatic/examined lymph node ratio (LN ratio) system can compensate for the shortcomings of the UICC/AJCC staging. Methods: Prospective data of 8949 primary T1-T4a gastric cancer patients who underwent curative surgery were reviewed. The patients were stratified by T-stage and grouped according to NexLN; 1 to 14 exLN denoted the first group and every subsequent 10 LNs thereafter. Numbers of LN and 5-year survival rates were analyzed according to NexLN. “The NR-staging system” was generated using 0.2 and 0.5 as the cut-off values of LN ratio and then compared with UICC/AJCC stages. Results: The proportion of advanced N-stage increased with NexLN. Survival and the LN ratio were constant regardless of NexLN when combining all N0-N3b patients, however, T2/3 and T4a patients showed an increasing tendency toward survival in N1/2 and N3a as NexLN increased, mainly due to a stage migration effect. The LN ratio system showed better patterns of distribution of the LN stage and survival graph. The power of the differential staging of the LN ratio system was fortified with higher NexLN. Conclusion: The relationship between NexLN and survival is probably affected by stage migration in a high-volume gastric cancer center. The LN ratio system could be a better option to compensate for this effect, and the value of the prognosis prediction in this system increases with a higher NexLN.

Despite the well-described benefits of laparoscopic surgery such as lower operative blood loss and enhanced postoperative recovery in gastric cancer surgery, the application of laparoscopic surgery in patients with locally advanced gastric cancer (AGC) remains elusive owing to a lack of clinical evidence. Recently, the Korean Laparoscopic Surgical Society Group launched a new multicenter randomized clinical trial (RCT) to compare laparoscopic and open D2 lymphadenectomy for patients with locally AGC. Here, we introduce the protocol of this clinical trial. This trial is an investigator-initiated, randomized, controlled, parallel group, non-inferiority trial. Gastric cancer patients diagnosed with primary tumors that have invaded into the muscle propria and not into an adjacent organ (cT2–cT4a) in preoperative studies are recruited. Another criterion for recruitment is no lymph node metastasis or limited perigastric lymph node (including lymph nodes around the left gastric artery) metastasis. A total 1,050 patients in both groups are required to statistically show non-inferiority of the laparoscopic approach with respect to the primary end-point, relapse-free survival of 3 years. Secondary outcomes include postoperative morbidity and mortality, postoperative recovery, quality of life, and overall survival. Surgeons who are validated through peer-review of their surgery videos can participate in this clinical trial. This clinical trial was designed to maintain the principles of a surgical clinical trial with internal validity for participating surgeons. Through the KLASS-02 RCT, we hope to show the efficacy of laparoscopic D2 lymphadenectomy in AGC patients compared with the open procedure. ClinicalTrial.gov, NCT01456598 .