Generally, the lymph nodes (LNs) in the splenic hilar region include the No. 4sa, No. 4sb, No. 10, and No. 11d LNs. This is an important segment in gastrectomy regarding D2 lymph node dissection in gastric cancer, particularly cancer located in the middle and upper third of the stomach (Fig. 6.1).

With respect to the relationship between the metastasis of the No. 4sa and No. 4sb LNs and the location of the tumor, it has been reported [1] that the rate of No. 4sa LNs metastasis (LNM) is 4.0–12.0 % for gastric body cancer and 19.0–36.0 % for the gastric fundus and cardial cancer. However, the incidence is relatively low for distal gastric cancer and is commonly <5.0 %. The metastatic rate of No. 4sb LNs is 18.0 %, 19.0 %, and 26.0 % in cardial, gastric body, and antrum cancer, respectively. Therefore, routine resection of the No. 4sa and No. 4sb LNs for advanced upper or middle gastric cancer and routine resection of the No. 4sb LNs for advanced lower gastric cancer are no longer controversial during D2 lymphadenectomy.

The ratio of No. 10 and No. 11 LNM has been reported to be 9.8–27.9 % [2–4] and 13.7–20.0 % [5, 6], respectively. A 346 case analysis for laparoscopic spleen-preserving No. 10 lymph node dissection for proximal gastric cancer by our center indicated that the incidence of No. 10 LNM is 10.1 % in advanced proximal gastric cancer [7]. No. 10 LNM is mainly associated with tumor location, depth of invasion, and Borrmann type [8]. The rate of gastric cancer in the upper and middle third of the stomach is significantly higher, particularly for advanced cancer located on the side with the greater curvature. No metastatic No. 10 and No. 11 LNs have been observed in early gastric cancer [9]. Our results [7] revealed that tumor location, depth of invasion, and metastases to No. 7 and No. 11 LNs were independent risk factors for No. 10 LNM. The status of No. 10 and No. 11 LNs is a significant prognostic factor for gastric cancer. It has been demonstrated that the 5-year survival rate of patients without metastases is 51.6 %, while that of patients with LNM is 11.0 % [10]. Therefore, dissection of the No. 10 and No. 11 LNs is necessary in advanced upper and middle gastric cancer. This approach is also suggested in the 3rd edition of Japanese Gastric Cancer Treatment Guidelines [11]. However, for advanced proximal gastric cancer located in the lesser curvature, without serosal invasion or No.7 and No. 11 LNM, whether there is a need to undergo No. 10 lymph node dissection demands further research [7]. In the 1990s, pancreaticosplenectomy was performed to entirely excise the No. 10 and No. 11 LNs. Prophylactic dissection of splenic hilar LNs by conducting such surgery increases the risk of complications associated with distal pancreatectomy such as pancreatitis, pancreatic fistula, intra-abdominal infection or abscess, and postoperative diabetes. It also does not significantly improve the 5-year survival rate (35.6 % vs. 42.2 %; P = 0.622) [12, 13]. Hence, some investigators have suggested that pancreaticosplenectomy cannot be used as a routine surgical method. In addition, the spleen and pancreas tail are only resected when obvious tumor invasion has been observed [14]. To achieve radical excision and avoid the complications caused by distal pancreatectomy as mentioned above, some investigators have advocated that it should be appropriate to exclusively perform pancreas-preserving splenic hilar lymph node dissection using splenectomy to cure upper and middle third gastric cancer. In recent years, researchers have gradually concentrated on the immunological aspects of the spleen, such as antitumor and anti-infection functions, which are also important in maintaining the health of patients. It is reported by Schwarz et al. [14] that, with the development of surgical techniques, spleen-preserving splenic hilar lymph node dissection has been demonstrated to be technically feasible, with a curative effect similar to splenectomy. And no survival benefits have been observed after splenectomy (48.3 % vs. 54.8 %; P = 0.503), while patient morbidity and mortality were significantly increased. In contrast, pancreas- and spleen-preserving lymph node dissection (D2) has achieved improved prognosis. Therefore, whether splenectomy should be performed requires careful consideration. The concept of spleen-preserving splenic hilar lymph node dissection is being accepted by an increasing number of clinicians.

In the clinic, the areas adjacent to the splenic hilar are complex and located in a narrow, but very deep, operating space. The spleen often adheres to the omentum or peritoneum, making it susceptible to injury. The vessels in the splenic hilar are particularly intricate and variable; thus, in open surgery, the spleen and distal pancreas must be pulled out of the abdomen, and the No. 10 LNs can then be dissected thoroughly. However, this manipulation is traumatic and time-consuming; moreover, spleen floating or twisting might occur after the operation. If the spleen and distal pancreas are not mobilized before splenic hilar region dissection, it can be difficult to radically remove the LNs because of the lack of adequate exposure. Laparoscopic amplification and the superior effects of ultrasonic scalpel for cutting and hemostasis allow the surgeon to clearly visualize the perigastric fascia, intrafascial space, vasculature, nerves, and other structures. The splenic vessels and their branches can thereby be comfortably exposed, and the meticulous procedure involved in No. 10 and No. 11 lymphadenectomy can be smoothly and efficiently completed. Therefore, the application of laparoscopy may have advantages in spleen-preserving splenic hilar lymph node dissection.

The first report of laparoscopic spleen-preserving splenic hilar lymph node dissection, regarding the treatment of gastric cancer in the upper and middle third of the stomach, was published by Hyung et al. [15] in 2008. A mean number of 2.7 (1–5) LNs per patient was found in the splenic hilar, and the effect of dissection was the same as that in open surgery. In addition, laparoscopic surgery provides obvious advantages including smaller incision, minimal invasiveness, and shorter operating time because of maintenance of the spleen in situ. In addition, it has been found that laparoscopic spleen-preserving splenic hilar lymphadenectomy is safe and feasible. In our study, the average number of retrieved LNs under laparoscopic surgery was 3.6 per patient, and no patients required open conversion resulting from injury to the spleen or its vessels; no complications associated with dissection of the splenic hilar region, such as hemorrhage, splenic ischemia, and splenic necrosis, have been observed postoperatively indicating favorable short-term outcomes [16]. It can be predicted that, with the improvement of standardized training and the development of laparoscopic techniques, laparoscopic spleen-preserving splenic hilar lymphadenectomy will become one of the standard treatments for advanced upper and middle gastric cancer.