The mainstay treatment of AEG II is surgery(11, 12), but the choice of surgical approach, the scope of lymph node dissection and the optimal extent of gastrectomy are still debatable(8, 9, 13). We conducted this study to analyze the different outcomes of surgical-related characteristics and survival rate between the transthoracic and transhiatal-abdominal approaches to explore optimal treatment for AEG II.
It has been reported that the incidence of postoperative complications of a transthoracic approach for AEG II is significantly higher than that of a transabdominal approach(7, 14, 15). In our study, the incidence of complications was significantly higher in the TT group than in the TH group (17.48% vs. 8.04%, P = 0.028), which may be explained by the fact that the transthoracic approach leads to more mechanical lung injury. In accordance with some previous work(15, 16), there was no significant difference in the incidence of other grade II complications or in anastomotic fistula and other serious complications (grade III-Ⅳ) between the two groups. Consequently, the 30-day postoperative mortality was not significantly different between the groups, indicating a similar safety with these two surgical approaches for AEG II.
Lymphatic drainage in AEG II occurs simultaneously to the thoracic cavity and abdominal cavity due to the location(17, 18). Previous studies have shown that a sufficient number and extent of lymph node dissection are independent risk factors affecting the long-term survival of patients(19, 20). Some studies have suggested that the transhiatal-abdominal approach can remove more lymph nodes(7, 21), though other studies have reported no difference between them(22). In this study, the total number of lymph nodes dissected in the TT group was slightly higher than that in the TH group, but with no significant difference, indicating that for total lymph node cleaning efficiency, the two surgical approach are essentially similar. In general, it is relatively difficult to dissect lymph nodes along the celiac artery, splenic artery and common hepatic artery with the transthoracic approach, especially the traditional left transthoracic approach, though middle and lower mediastinal lymph nodes are accessible. In this study, the thoracic lymph node metastasis rate in the TT group was 14.7%, indicating that mediastinal lymph node dissection is necessary for AEG II surgery.
The incidence of positive proximal margins in the TH group was significantly higher than that in the TT group. This result was consistent with Parry K et al(23), suggesting that the transthoracic approach is related to a higher average resection length of the esophagus and R0 resection rate(24). Combined with previous reports(24, 25), the transthoracic approach appears to be suitable with esophageal invasion of 3 cm or more for AEG II. In the present study, the hospitalization time of patients undergoing the transhiatal-abdominal approach was shorter than that of patients undergoing transthoracic surgery, consistent with previous reports(7, 8). These findings indicate that compared with the transthoracic approach, the transabdominal approach involves less trauma, less influence on respiratory function and faster recovery. Therefore, the transabdominal approach is more suitable for patients in a relatively poor general condition, especially those with poor pulmonary function.
Table 5: Survival related multivariate analysis
Variable
|
5-year survival related factors
|
P
|
multivariate analysis
|
P
|
HR
|
CI 95%
|
HR
|
CI 95%
|
Gender (Male vs Female)
|
1.255
|
(0.817-1.926)
|
0.299
|
-
|
-
|
-
|
Age (>=65 VS <65)
|
1.238
|
(0.901-1.702)
|
0.187
|
-
|
-
|
-
|
T stage
|
|
|
|
|
|
|
2(reference)
|
1
|
-
|
-
|
1
|
-
|
-
|
3
|
3.396
|
(1.779-6.480)
|
<0.001
|
1.997
|
(1.010-3.948)
|
0.047
|
4
|
6.919
|
(3.314-14.447)
|
<0.001
|
3.234
|
(1.468-7.122)
|
0.004
|
N stage
|
|
|
|
|
|
|
0(reference)
|
1
|
-
|
-
|
1
|
-
|
-
|
1
|
2.897
|
(1.768-4.747)
|
<0.001
|
2.506
|
(1.513-4.150)
|
<0.001
|
2
|
2.918
|
(1.759-4.840)
|
<0.001
|
2.436
|
(1.450-4.094)
|
0.001
|
3
|
6.927
|
(4.218-11.375)
|
<0.001
|
5.136
|
(3.042-8.671)
|
<0.001
|
Histological differentiation
|
|
|
|
|
|
|
High(reference)
|
1
|
-
|
-
|
1
|
-
|
-
|
Mid
|
2.545
|
(0.352-18.394)
|
0.335
|
-
|
-
|
-
|
Poor
|
4.106
|
(0.572-29.454)
|
0.160
|
-
|
-
|
|
Gastrectomy (total/partial)
|
1.393
|
(1.014-1.913)
|
0.041
|
1.091
|
(0.789-1.509)
|
0.597
|
Surgery approach (TT/TH)
|
1.095
|
(0.795-1.507)
|
0.579
|
-
|
-
|
-
|
P < 0.05 in univariate analysis or previous research proved the variable related to prognosis were included in multivariate analysis |
Overall, the influence of a surgical approach on the long-term survival of patients is an important factor to evaluate its rational use, and results in previous studies are controversial. For example, Susan et al(26) searched an institutional prospectively maintained database and found the survival time of the transabdominal approach to be shorter than that of the right thoracoabdominal approach for AEG II, but this result may be related to the higher proportion of elderly patients over 70 years old in the transhiatal-abdominal approach group. The JCOG9502(16) study showed that the median survival time and five-year survival rate of patients undergoing the transhiatal-abdominal approach were slightly higher than those of patients undergoing the left thoracoabdominal approach, but with no significant difference. In addition, Parry K et al(23) reported no difference in five-year survival rate between the transhiatal-abdominal and transthoracic approach, similar to our results. Indeed, subgroup analysis of gastrectomy revealed no significant difference in five-year survival between the subgroups. Therefore, we hold the opinion that the long-term effects of transthoracic and transabdominal approaches are similar for the surgical treatment of AEG II.
The optimal extent of gastrectomy for Siewert type II AEG, including total and partial gastrectomy, is always selected according to tumor size, stage, location and surgeon's preference. Zhao et al(27) analyzed the effects of transhiatal-abdominal total and partial gastrectomy on patients and concluded that the latter may have a better five-year survival rate in AEG II patients at IA-IIIA stage and a tumor diameter less than 3 cm; for patients at later stages, the extent of gastrectomy had no significant impact on long-term prognosis. Similarly, we conclude that for locally advanced AEG II, patients who underwent partial gastrectomy had a higher five-year survival rate than those who underwent total gastrectomy (44.8% vs. 36.1%, P = 0.038). In subgroup analysis, we also found that patients treated with partial gastrectomy had a higher survival advantage than those treated with total gastrectomy. We believed this was related to the choice of surgical method, as the tumor stage of the patients treated with total gastrectomy was later. Survival-related multivariate analysis in this study showed T stage and N stage to be independent risk factors affecting the prognosis of AEG II patients, and we consider tumor stage as the main factor related to the survival of these patients.
This study is a single-center retrospective study. Although relatively strict screening conditions were set, there may be a certain degree of selection bias, and the qualified sample size was relatively small. A prospective study needs to be designed to obtain more objective results.