| Backgrouds:A consensus regarding surgical procedure of esophagogastric junction(EGJ)adenocarcinoma has been reached based on two randomized trials.Ivor-Lewis esophagectomy is standard treatment for Siewert ?,whereas transhiatal extended gastrectomy for Siewert ?.Siewert ? is almost the same as EGJ carcinoma of Nishi's definition,and nodal metastasis frequently involved the abdominal and mediastinal stations.In fact,even for the same Siewert ? tumors at the EGJ,thoracic surgeons prefer Ivor-Lewis esophagectomy,whereas gastric surgeons prefer extended gastrectomy.Coincidentally,the long-term survival rates between two procedures are comparable based on two well-known randomized controlled trials.However,the extent of gastrectomy and lymphadenectomy of the two is obviously different.Thus,this study aimed to determine the extent of gastrectomy and lymphadenectomy for Siewert type ? EGJ carinoma.We adopted the efficiency index(EI)calculated by multiplying of the frequency of metastasis to each station and the 5-year survival rate of patients with metastasis to that station.All lymph nodes were classified into three categories according to metastatic rates:LNM-1 nodes(strongly recommended for dissection),rates more than 10%;LNM-2 nodes(weakly recommended for dissection),rates from 5%to 10%;and LNM-3 nodes(not recommended for dissection),rates less than 5%.According to the EI,lymph nodes were divided into four categories:EI-1 nodes(should be resected in every case),El exceeding 5%;EI-2 nodes(should be resected as far as practicable),El from 2%to 5%;EI-3 nodes(need not be resected if a patient is at high risk for mortality and morbidity),El from 0.5%to 2%,divided into EI-3A(1%?2%)and EI-3B(0.5%?1%);EI-4 nodes(need not be resected in any case),El less than 0.5%.Therefore,the nodes with a rate exceeding 5%and El over 2%should be routinely required for dissection.Chapter 1 Transhiatal Total Gastrectomy versus Proximal Gastrectomy for Esophagogastric Junction Adenocarcinoma:A Retrospective Long-term OutcomeObjective:To compare the 5-year overall survival between transhiatal proximal gastrectomy(THPG)and total gastrectomy(THTG)for patients with EGJ carcinoma.Methods:Between January 2004,and August 2015,306 patients with Siewert II tumors were divided into the THTG group(n=148)and the THPG group(n=158).Their long-term survival was compared according to Nishi's classification.The Kaplan-Meier and Cox proportional hazards models were used for survival analysis.Results:There were no significant differences between the two groups in the distribution of age,gender,tumor size or Nishi's type(P>0.05).However,a difference was observed in terms of pathological tumor stage(P<0.05).The 5-year overall survival rates were 62.0%in the THPG group and 59.5%in the THTG group.The hazard ratio for death was 0.455(95%CI,0.337 to 0.613;log-rank P<0.001).Type GE/E=G showed a worse prognosis compared with Type G(P<0.05).Subgroup analysis stratified by Nishi's subtype,stage IA-IIB and ? A,and tumor size less than 3 cm indicated that THPG group had survival advantages over the THPG group(P<0.05).However,it failed to show a survival benefit in stage ?B(P>0.05).Conclusions:Nishi's definition is an effective method to clarify the subdivision of Siewert ? adenocarcinoma into above or below the EGJ line.Transhiatal proximal gastrectomy is an optimal procedure for the selective cases with EGJ tumors of less than stage ?B(T1?T4a and NO-N2),wheras total gastrectomy is required for that of greater than stage ?B(T4b and N3).Chapter 2 Efficacy of Lymph Node Dissection by Node Zones for Esophagogastric Junction Carcinoma:Findings of an International SurveyObjective:To determine the required extent of lymph node dissection for EGJ carcinomas.Methods:Observational studies evaluating the lymph node metastasis(LNM)and the therapeutic efficiency index(EI)from nodal dissection of each station in EGJ tumors and published in English were identified via Pubmed,Embase,and Cochrane database until December 2019.Data were extracted and synthesized narratively.Results:23 eligible studies included 8885 cases with Siewert ??? type EGJ carcinoma according to Siewert or Nishi's classification.Type ? accounted for 82.3%,whereas type III and I for 0.4%and 17.3%,adenocarcinoma for 91.4%and squamous carcinoma for 8.6%.Overall,LNM-1 nodes included No.1(38.2%),No.2(22.9%),No.3(40.3%),No.7(21.5%),No.9(11.2%),No.11p(10.9%)and No.16a2/b1(10.9%),whereas LNM-2 nodes included No.8a(5.6%)and No.10(5%)nodes,and LNM-3 nodes included Nos.4sa-4d(1%-3%),No.5(1.5%),No.6(1.1%),No.11d(2.4%),No.12a(1.2%)and Nos.19-20(<1%).EI exceeded the 5%at the No.1(13.8),No.2(8.4),No.3(16.0)and No.7(6.9)nodes,the order being consistent with that of metastatic incidence.Modest values were gained by dissection of No.11p(2.9),No.9(2.8),No.8a(1.4),and No.10(1.2)nodes,in that order,whereas the EI for the distal perigastric Nos.4sa?6 nodes were low(0?0.6),and the value was only marginal for the resting stations including Nos.11d,12a,16a2/b1,19 and 20 nodes.Mediastinal LNM-1 nodes only included No.110 nodes(17.2%),and the EI was 4.5.However,the value was only marginal zero for the remaining assigned to LNM-3 nodes with Nos.105?112(0.3%?4%)nodes.Limited to Siewert ? tumor,LNM-1 nodes included No.1(35.3%),No.2(20.9%),No.3(34.7%),No.7(19.8%)and No.11p(10.1%)nodes;LNM-2 included No.9(8.0%);LNM-3 included Nos.4sa?6(0.7%?2.1%),No.8a(3.7%),No.10(3.4%),No.11d(0.8%),No.12a(1.2%),No.16a2(2.5%),No.19(0.6%)and No.20(1.0%)nodes.Mediastinal LNM-1 nodes only included No.110 nodes(12.4%),and the EI value was 4.5.However,the resting of Nos.105-112(0%?1.5%)were assigned to LNM-3 nodes,and the index were only marginal.The nodes including Nos.1,2,3,7,9,11p and 110 should be routinely dissected in any case with EGJ carcinoma.For selective cases with larger tumor and at low risk,the distal perigastric and middle or supperior mediastinal dissections depended on the distance from EGJ to the proximal or distal end of the tumor respectively.Conclusions:Proximal gastrectomy should be the minimum requirement in any case with EGJ cancer confined to the upper stomach.In contrast,total gastrectomy is required in that transcending the upper stomach.Similarly,the inferior mediastinal dissection is minimum requirement in any case with esophageal involvement of 3 cm or less,whereas the superior and middle mediastinal dissection is not routinely required unless in the selective cases with esophageal involvement exceeding 3 cm.Chapter 3 Similarities and Differences in the Pattern of Lymph Node Metastasis and Efficacy of Lymph Node Dissection between Siewert ? and ? Carcinoma of Esophagogastric JunctionObjective:To clarify the extent of lymphadenectomy between the two types.Methods:Observational studies evaluating the lymph node metastasis(LNM)and the efficiency index(EI)from lymph node dissection of each station in Siewert ?and ? EGJ tumors and published in English were identified via Pubmed,Embase,and Cochrane database until December 2019.After extracting and synthesizing the LNM or El narratively,the required extent of lymph node dissection was compared between Siewert ? and ?carcinomas in terms of the nodes with EI more than 2%.Results:7532 patients with Siewert ? or ? carcinoma from 17 eligible articles were included into the study.Siewert ? accounted for 85%,whereas Siewert ? for 15%,adenocarcinoma for 87.6%and squamous carcinomas for 12.4%.The required extent of D2 lymphadenectomy in Siewert ? EGJ carcinoma of LNM?5%and EI?2%included the sites of Nos.1,2,3,7,9,11p,110,while those of Siewert ? carcinoma were Nos.1,2,3,4sa,4sb,4d,7,8a,9,10,11p,16a2,110.Both groups showed the similar-high rates at LNM-1 nodes in terms of Nos.1,3,2,7,11p(P>0.05).Compared with Siewert ?,the rate of LNM was significantly higher at No.3 nodes in Siewert ?(37.0%vs.63.5%,P<0.001).Both groups also showed distinctly differences in the Nos.8a-10 nodes assigned to LNM-2 or LNM-3 nodes in type ?,whereas LNM-1 nodes with a marked upward rate in type ?(P<0.01-0.09).The metastatic rates in type ? were significantly higher than that in type ? at Nos.4sa?6 nodes(5%?10%vs.0%?2%,P<0.05),respectively.Accordingly,they were assigned to LNM-1 or LNM-2 nodes in type ?,but only to LNM-3 in type ?.Overall,the El was consistent with that of the corresponding LNM rate.However,the index of type ? was significantly higher than that of type ? at No.3,Nos.4sb?4d,No.7,No.9 and No.10 nodes(P<0.05),respectively.Conclusions:The similar-highest efficiency nodal stations to be dissected for patients with Siewert ? and ? carcinoma were the paracardial and lesser curvature nodes(Nos.1?3),the nodes at the root of left gastric artery(No.7),and the nodes at proximal splenic artery(No.11p),regardless of Siewert subtype,but the subsequent efficiency including Nos.8a,9,10 and Nos.4a?6 nodes was different depending on the subtype.Total gastrectomy should be routinely required as a standard treatment for Siewert type III tumor,whereas in Siewert II,proximal gastrectomy with inferior mediastinal dissection may be an optimal procedure. |
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