Clinicopathological Characteristics Of Lymph Node Metastasis To No.5 And No.6 In Upper Two-thirds Gastric Adenocarcinoma

Aim:To investigate the metastatic rate and related clinicopathological factors of No.5 and No.6 lymph nodes in the patients with gastric adenocarcinoma located in the upper two-thirds stomach.And to evaluate the feasibility of performing proximal gastrectomy for these patients.Method : The clinical data of the patients who had undergone total gastrectomy(TG)with D2 lymphadenectomy from January 2008 to December 2017 were retrospectively collected.A total of 564 patients were included after screening.Clinicopathological factors were analyzed to identify the predictive factors for No.5 and No.6 lymph node metastasis(LNM).Results: No.5 or No.6 LNM occured in 95 of 564 patients(16.84%).The metastatic rates of No.5 and No.6 lymph node were the lowest among the NO1-9 lymph node groups.Univariate analysis showed that the location of the lesion,pathological types,degree of differentiation,Borrmannclassification,vascular or neurological invasion,tumor diameter,depth of invasion,the other perigastric LNM except No.5 and No.6,N stage,and TNM stage were the risk factors for No.5 or No.6 LNM.Multivariate analysis showed that depth of tumor invasion(OR=1.621,95% CI1.023-2.568,P=0.040),tumor location(OR=3.221,95% CI 1.646-6.303,P=0.001),tumor diameter ≥ 4 cm(OR =4.250,95% CI 2.027-8.909,P<0.001),pathological types(OR=1.972,95% CI 1.064-3.652,P=0.031),No.4 LNM(OR=5.450,95% CI 3.010-9.869,P < 0.001)and No.7,8,9LNM(OR = 4.665,95% CI 2.511-8.666,P < 0.001)were independent risk factors of No.5 and No.6 LNM.As for 118 T2 and T3 patients,the metastatic rate of No.5 or No.6 lymph node was 3.39%(4/118).There was no significant difference in the rate of LNM compared with T1 group(2.04%,2/98).Meanwhile,location of the lesion and No.4 LNM were risk factors for No.5 or No.6 LNM in T2 and T3 patients.Preoperative enhanced CT has good accuracy in the prediction of gastric lymph node metastasis(68.27%-96.15%),but it is relatively inconsistent compared with pathological examination(Kappa Value:0.330-0.581).Conclusion: The rate of No.5 and No.6 lymph node metastasis in upper 2/3gastric adenocarcinoma is low,and it is significantly related to tumor location,pathological types,tumor diameter,tumor invasion depth,No.4 lymph nodemetastasis,and No.7,8,9 Lymph node metastasis.For T2 and T3 patients with tumors located in the EGJ region and without No.4 lymph node metastasis,the metastasis rate of the No.5 and No.6 lymph nodes was lower and similar to that of early gastric cancer.Preoperative enhanced CT scan has limited value in detecting the existence of gastric lymph node metastasis(especially No.5 and No.6 lymph nodes).For patients with T2 and T3 who have tumors located in the EGJ region and no lymph node metastasis(especially No.4,No.5,and No.6)found by preoperative and intraoperative examination,the strategy of undertaking proximal Gastrectomy with D1 or D1+ lymph node dissection + postoperative adjuvant therapy can be considered.