Clinical features of metastasis from superficial squamous cell carcinoma of the thoracic esophagus.

Background: It is important to understand the sites and the frequency of metastasis to perform less invasive treatments for superficial esophageal cancer, such as minimized or focused lymphadenectomy, endoscopic resection, and chemoradiotherapy. The distribution pattern and frequency of metastases from superficial esophageal cancer, however, have not been well elucidated.

Methods: In 342 patients with superficial esophageal squamous cell carcinoma who underwent esophagectomy, the sites and frequency of any metastasis, including lymph node metastasis at the time of esophagectomy, lymph node recurrence, and hematologic metastases were investigated. Factors associated with the likelihood of metastasis and prognosis were also examined.

Results: The incidence of lymph node metastasis increased with tumor depth (m2 = 7%; m3 = 17%; sm1 = 29%; sm2 = 41%; and sm3 = 42%). Lymph node metastases were observed most frequently in upper mediastinal lymph nodes, such as upper paratracheal lymph nodes, and in perigastric lymph nodes, such as paracardial lymph nodes and the left gastric lymph nodes. Lymph node metastases were also observed across a broad range of lymph nodes, including cervical, mediastinal, and abdominal lymph node regions, irrespective of tumor location. The 5-year overall survival and disease-specific survival rates were 78% and 89%, respectively. Submucosal invasion and lymphatic invasion were identified as independent factors associated with metastasis. Lymphatic invasion was also identified as an independent factor associated with disease-specific survival.

Conclusion: The present study shows that metastasis can occur in a wide range of lymph node stations even in superficial esophageal squamous cell carcinoma. Together with the finding that lymphatic invasion is an independent prognostic factor, this study may help determine the treatment strategy for superficial esophageal squamous cell carcinoma.