Early squamous cell carcinoma of the oesophagus: the Japanese viewpoint

In Japan, more than 90% of oesophageal malignancies are squamous cell carcinomas, and superficial and early carcinomas now account for about 40% and 20%, respectively, of all oesophageal carcinomas. Definition of early carcinoma has changed on the basis of new data. As of 2007, early carcinoma is defined as intramucosal carcinoma with or without metastasis. In the subclassification based on depth of cancer invasion, m1 and m2 carcinomas have no metastasis and are considered curable by endoscopic mucosal resection alone, whereas < 10% of m3 carcinomas and about 20% of sm1 carcinomas have lymph node metastasis. The relationship between various pathological findings and the incidence of lymph node metastasis has been reviewed. High-grade squamous dysplasia (squamous cell carcinoma in situ in Japan) requires surgical or endoscopic removal. Very minute carcinomas have recently been detected by magnifying endoscopy and/or narrowband imaging. Endocytoscopy could replace biopsy histopathological examination for diagnosis of oesophageal squamous cell carcinoma, and endocytoscopic diagnosis and endoscopic therapy may be performed simultaneously. As a result of advances in the development of endoscopes, pathologists are now expected to diagnose very minute lesions, < 1 mm in size, in the oesophagus.