Reply to the Letter: "Should Adenocarcinoma of the Esophagogastric Junction Be Classified as Gastric or Esophageal Cancer, or Else as a Distinct Clinical Entity?"

Comprehensive Molecular Characterization of Adenocarcinoma of the Gastroesophageal Junction Between Esophageal and Gastric Adenocarcinomas

OBJECTIVE

To investigate the molecular characteristics of AGEJ compared with EAC and gastric adenocarcinoma.

SUMMARY OF BACKGROUND DATA

Classification of AGEJ based on differential molecular characteristics between EAC and gastric adenocarcinoma has been long-standing controversy but rarely conducted due to anatomical ambiguity and epidemiologic difference.

METHODS

The molecular classification model with Bayesian compound covariate predictor was developed based on differential mRNA expression of EAC (N = 78) and GCFB (N = 102) from the Cancer Genome Atlas (TCGA) cohort. AGEJ/cardia (N = 48) in TCGA cohort and AGEJ/upper third GC (N = 46 pairs) in Seoul National University cohort were classified into the EAC-like or GCFB-like groups whose genomic, transcriptomic, and proteomic characteristics were compared.

RESULTS

AGEJ in both cohorts was similarly classified as EAC-like (31.2%) or GCFB-like (68.8%) based on the 400-gene classifier. The GCFB-like group showed significantly activated phosphoinositide 3-kinase-AKT signaling with decreased expression of ERBB2. The EAC-like group presented significantly different alternative splicing including the skipped exon of RPS24, a significantly higher copy number amplification including ERBB2 amplification, and increased protein expression of ERBB2 and EGFR compared with GCFB-like group. High-throughput 3D drug test using independent cell lines revealed that the EAC-like group showed a significantly better response to lapatinib than the GCFB-like group (P = 0.015).

CONCLUSIONS

AGEJ was the combined entity of the EAC-like and GCFB-like groups with consistently different molecular characteristics in both Seoul National University and TCGA cohorts. The EAC-like group with a high Bayesian compound covariate predictor score could be effectively targeted by dual inhibition of ERBB2 and EGFR.

Serum tumor-associated glycoprotein 72, a helpful predictor of lymph nodes invasion in esophagogastric junction adenocarcinoma

Disruption of cell-cell junction and adhesion to vessels are crucial steps in tumor metastasis. Tumor-associated glycoprotein 72 (TAG-72) is a crucial membrane mucin in gastroesophageal mucosa for microenvironment contact with cells. Thus, the TAG-72 value may be an indicator of the malignant involvement of lymph nodes in esophagogastric junction adenocarcinoma (EGAC) patients. Of the 183 patients suspected as gastroesophageal neoplasms, 129 were subsequently diagnosed as EGAC, and 54 were subsequently diagnosed as benign gastroesophageal diseases by imageological or/and histological examination. After we obtained preoperative serum TAG-72 values, the relationship between serum TAG-72 and lymphatic metastasis status, extent of invaded lymph nodes and clinical stage was tested using Spearman correlation analysis and χ2 tests. Compared with those in patients who suffered either benign gastroesophageal diseases or preinvasive carcinoma, the median serum TAG-72 values were statistically higher in EGAC patients with positive lymph nodes (Kruskal-Wallis test; P < 0.001). Serum TAG-72 values were significantly correlated with Lymph Node Ratio (LNR) (Spearman correlation; P < 0.001). Using corresponding ROC (95% CI = 0.621-0.783, P < 0.0001), serum TAG-72 values with an optimal cut-off (2.2 kU/mL) showed a sensitivity of 0.632 and a specificity of 0.690 for predicting malignant lymph node involvement in EGAC. These results suggest that the serum TAG-72 value is a clinically helpful predictor of lymph nodes invasion in resectable EGAC.

Surgical approach for Siewert type II adenocarcinoma of the esophagogastric junction: transthoracic or transabdominal? -a single-center retrospective study

Background

The surgical approach (transthoracic or transabdominal) for patients with Siewert type II adenocarcinoma of the esophagogastric junction (AEG) still remains controversial.

Methods

Data of patients with Siewert type II AEG were collected in the Guangdong General Hospital from 2004 to 2014 and we compared their clinicopathological outcome and prognosis in regard to the transthoracic (TT) and transabdominal (TA) approach.

Results

A total of 158 patients with Siewert type II AEG were analyzed and our results demonstrated that their overall medium survival was 52 months. Also, their 5-year overall survival rate was 39.1%, which was comparable between the TT and TA group (35.1% vs. 43.2%, P>0.05), while more lymph nodes were dissected in TA group (23.7±0.2 vs. 18.1±0.3, P<0.05), with less postoperative complications (14.3% vs. 28.4%, P<0.05) and shorten hospital stay (12±4 vs. 15±7 d, P<0.05).

Conclusions

For patients with Siewert type II AEG, the TA approach is more suitable to achieve an optimal extent of lymph node dissection, reduction in the incidence of complication, shorten hospital stay, and to promote the recovery.

Recurrence Pattern and Lymph Node Metastasis of Adenocarcinoma at the Esophagogastric Junction

BACKGROUND

The surgical approach for adenocarcinoma of the esophagogastric junction (AEJ) still is controversial despite revised tumor-node-metastasis (TNM) classification. This study aimed to evaluate the oncologic outcome of a routine transhiatal approach for AEJ in terms of recurrence and lymph node (LN) metastasis of AEJ.

METHODS

Recurrence patterns and LN metastasis of a single, primary AEJ (n = 463) treated by a surgical resection using a transhiatal approach without routine complete mediastinal LN dissection or routine splenectomy were analyzed respectively. To validate current treatment for recurrence, a validation index of recurrence (ViR; overall survival/incidence of solitary recurrence factor) was developed.

RESULTS

The overall recurrence rate for AEJ was 20.3%, which did not differ significantly between AEJ II (20.8%; n = 125) and AEJ III (20.1%; n = 338). Mediastinal recurrence did not differ significantly among the subtypes of AEJ, irrespective of gastroesophageal junction involvement. Splenic hilar LN recurrence-free survival did not differ significantly between the gastrectomy-only group, the gastrectomy-plus-splenectomy group, and the gastrectomy plus distal pancreatectomy group. The solitary recurrence rate for the mediastinal LN was 0.7% for AEJ, and the overall median survival with that recurrence was 30.5 months. The ViR for mediastinal LN recurrence (43.6) was higher than for regional LN (20.9) or distant LN (14.6) metastasis.

CONCLUSION

In terms of LN metastasis and recurrence, a transhiatal approach without complete mediastinal LN dissection can be acceptable, and routine splenectomy is not necessary for AEJ II or AEJ III arising within the stomach.