The aim of this study was to clarify the clinicopathological characteristics of cancers around the EGJ, and to investigate optimal management. Standard treatment for EGJC is controversial for several reasons. One of them is that the definition of EGJC is not stable. Siewert et al. define EGJC as adenocarcinoma, centered in area between the lowest 5 cm of the esophagus and the upper 5 cm of the stomach, and crossing the EGJ . The Japanese Classification of Esophageal Cancer (JCEC) from the Japan Esophageal Society defines EGJC as being within the lower 2 cm of the esophagus and the upper 2 cm of the stomach, because of histological evidence of spreading of columnar epithelium-lined lower esophagus . Moreover, AJCC defines EGJ as including squamous-cell carcinoma in the same locations as with Siewert classification .
However Siewert classification is widely used, its application is limited for adenocarcinoma. Although EGJC, as defined by the AJCC cancer staging manual, includes squamous-cell carcinoma, it does not categorize any tumor without EGJ invasion as EGJC—as does Siewert classification. Although it estimates prognosis well using different staging systems for squamous-cell carcinoma and adenocarcinoma, this method may be too complex for clinicians; whereas the JCEC system, which treats most limited tumors as EGJC, is more precise.
Because of the unstable definition of EGJCs, clinicopathological characters and treatment strategies have not been unified. Siewert et al. argued that complete surgical resection and lymph node metastasis were independent prognostic factors in type II adenocarcinoma, and subtotal esophagectomy had less survival effectiveness for the patients with type II adenocarcinoma . Hasegawa et al. reported that about 40%, 60% and 90% of patients with type I, II and III tumors, respectively, had lymph node metastases, and recommended complete resection for improving survival . Schiesser et al. reported that subtotal esophagectomy and extended total gastrectomy should be performed for type I and type II–III tumor . With regard to surgical approach, Sasako et al. showed that the left thoracoabdominal approach did not improve survival after the abdominal-transhiatal approach and leads to increased morbidity in patients with cancer of the cardia or subcardia . Kakeji et al. reported that esophagectomy with mediastinal and abdominal lymphadenectomy was adequate for squamous-cell carcinoma, and that extended total gastrectomy with lower mediastinal and abdominal lymphadenectomy was suitable for adenocarcinoma . Carboni et al. maintained effects of extended gastrectomy by an abdominal–trans-hiatal approach for EGJC . Conversely, Chau et al. reported that performance status, liver metastasis, peritoneal metastasis and alkaline phosphatase were independent prognostic factors in patients with locally advanced and metastatic EGJC, and that prognoses of patients with recurrent disease were no better than those without surgery .
We studied any tumor centered in area between the lowest 5 cm of the esophagus and the upper 5 cm of the stomach, regardless of histological type and EGJ invasion, and simply categorized them in 4 groups including type E (SQ), E (AD), Ge and G.
Whereas type E (SQ), E (AD) and Ge tumors in this study are categorized as esophageal cancer by AJCC/UICC criteria, these tumor groups show differences in clinicopathological characteristics. In lymph node metastasis, approximately 60%, 50%, 70% and 30% of the patients with type E (SQ), E (AD), Ge and G tumors respectively had lymph node metastases in this study. Cervical lymph node metastases were recognized in only type E (SQ) tumor group. Because type E (AD) tumor was based on columnar epithelium, its histological behavior was thought to be similar to cardiac adenocarcinoma; however, type E (AD) tumor showed a nodal metastatic spreading pattern similar to that of type Ge tumor in this study. Although it seems reasonable to unite type E (AD) and Ge tumors as a group on the basis of lymphadenectomy extent, the patients with type E (AD) tumor showed significantly lower survival rates than other type tumor groups. Although not significantly, patients with type E (AD) tumor had higher incidence of nodal metastasis at mediastinal lymph node than did patients in tumor groups, and all mediastinal positive nodes existed in lower mediastinal area. Thus, subtotal esophagectomy is not necessary for type E (AD) and Ge tumor, if complete tumor resection can be achieved. Because no cervical or mediastinal lymph node metastasis was recognized in the type G tumor group, we should not perform subtotal esophagectomy for type G tumor. In multivariate analysys, tumor type (type E (AD)) was an independent risk factor for survival of the patients with EGJC in this study. The prognosis of cervical or mediastinal node positive patients was poor. Because survival benefit by cervical and mediastinal lymphadenectomy for the node positive patients with EGJC is limited, we should carefully perform subtotal esophagectomy, and cervical and mediastinal lymphadenectomy for EGJC patients. Therefore, extended gastrectomy with or without lower esophagectomy, according to tumor location, and lower mediastinal and abdominal lymphadenectomy is thought to be adequate for patients with EGJC, including type E (SQ) tumor.
Although lymphatic invasion, venous invasion, depth of tumor invasion (T category), lymph node metastasis (N category) and distant metastasis (M category) were significantly prognostic factors in the univariate analysis, tumor type (types E (SQ), E (AD), Ge and G) and depth of tumor invasion (pT3–4 tumor) were significant in the multivariate analysis in this study. It was reported that complete surgical resection and lymph node metastasis were independent prognostic factors in type II adenocarcinoma . We believe that the lack of a significant difference between the prognosis and lymph node metastasis can be explained by limitations of this study such as the small sample size. Distant metastasis (M category) was not significantly prognostic factor in the multivariate analysis in study. AJCC/UICC TNM staging system for esophageal cancer defines nodal metastasis along lesser curvature as distant metastasis, although lymph node along lesser curvature is one of the main regional lymph nodes of gastric cancer. Because majority of the patient with M1 disease had no hematogenous metastasis in this study, there was a possibility that distant metastasis was not significant for prognosis in this study.
Reim et al. reported that chemotherapy to be more efficacious for EGJC than for distal gastric cancer . The treatment efficacy of chemotherapy before or after surgery is unclear in this small scale retrospective cohort study. To clarify optimal treatment strategy for EGJC, we should confirm the results in this study using a large scale prospective study.