Nodal involvement significantly affected the prognosis of GC patients because it is the major root of tumor relapse after surgery[14, 15]. Thus, standardized lymph nodes dissection is the basic requirement for curative (R0) gastrectomy. Curative gastrectomy with D2 lymphadenectomy has been considered as the standard fashion for decades in eastern Asia, especially in Japan[16, 17]. This procedure has been gradually accepted by Western countries in recent years[18, 19]. As for the RLNs count, the 8th edition TNM classification for GC recommended dissecting at least 16 lymph nodes. Moreover, emerging evidence revealed the positive correlations between RLNs count and overall survival of GC patients[4, 5, 20]. By comparing RLNs count to survival time, Okajima et al. suggested an optimal RLNs count of ≥ 25; Deng et al. proposed an optimal RLNs count of ≥ 16 for lymph node-negative GC and > 30 for lymph node-positive GC by stratum analysis of 7,620 patients; Sano et al. reported that RLNs count preferably achieved 30 or more by a multicenter study enrolling 25,411 patients. These above studies mainly focused on the relationship between RLNs count and long-term prognosis. However, little is known about its effects on postoperative short-term complications.
In this study, we concentrated on the association between RLNs count and short-term prognosis. Univariate analyses showed no significant difference between RLNs count and postoperative complications (both overall and stratified by CDC grade). Furthermore, it had no effect on postoperative stay and total hospital charges, although it would prolong the operation time. Therefore, more lymph nodes were encouraged to be dissected from the perspective of short-term prognostic.
Although curative gastrectomy with D2 lymphadenectomy is considered a pivotal strategy for advanced GC, there are international and institutional differences in the number of RLNs count [21, 22]. Various factors were reported to influence the RLNs count, including the confidence and enthusiasm of doctors (both surgeons and pathologists), surgical situation, and innate lymph node count in each patient[8, 10]. In our study, we concluded that RLNs count was related to preoperative serum albumin, type of resection, operation time, tumor invasion, lymph node metastasis, and pTNM stage were associated with RLN count. Of note, RLNs count was positively correlated with the lymph node metastasis rate, which underlined the importance of RLNs count for accurate staging.
Actually, for a thorough pathological examination, RLNs should be individually divided from a complete tissue sample after surgery. Owing to much time and effort was required during this procedure, it has not been widely implemented clinically. Therefore, the examined lymph nodes count by pathologists might be lower than the dissected lymph nodes count. Multiple attempts have been conducted to improve the detection rate of lymph nodes[23–25]. Li et al. elucidated that the mean number of RLNs could be significantly elevated by injecting carbon nanoparticles before surgery compared with controls (38.33 vs 28.27). Bruno and colleagues reported a twofold lymph node pick up rate utilizing methylene blue staining than unstained groups (35 vs 17). Several dye materials were also used to increase the number of lymph nodes dissected during surgery, such as fluorescent indocyanine green (ICG) and 5-aminolevulinic acid (5-ALA)[26, 27].
We acknowledge that this study had some potential limitations. First, it was a retrospective, single center study, so the results might be flawed because of residual confounding factors. Second, the RLNs count was closely related to the quality of surgeons and pathologists. The perioperative variables might differ in different doctors. Therefore, multi-center studies are needed to confirm our results.