High-Frequency Endoscopic Ultrasonography in the Evaluation of Superficial Esophageal Cancer

Objectives

Recently, there has been an increase in the detection of superficial esophageal cancer, and the 5-year survival rate in patients with m-type mucosal cancer is much higher than that of patients with sm-type cancer invading the submucosa. Since the frequency of lymph node metastasis with m-type tumors is lower than with sm cancers, endoscopic treatment such as endoscopic mucosal resection (EMR) has been carried out in patients with the former type. The Japanese Society of Esophageal Diseases carried out a survey of the histopathological results in 2418 cases of untreated superficial esophageal cancers resected by operation or EMR in 143 hospitals during 1990 - 1994 [1]. EMR was carried out in 394 patients, while the other patients underwent conventional surgery. The depth of cancer invasion was classified according to six categories: cancer limited to the epithelium was described as m1; cancer limited to the lamina propria was m2; invasion reaching the muscularis mucosa or invading the muscularis mucosa was m3; invasion of the submucosa to less than 200 µm was sm1; that reaching the proper muscle was classed as sm3; and invasion between sm1 and sm3 was sm2 (Figure [1]). The rates of lymph node metastasis in m1 and m2 cancers were less than about 5 %, those of m3 and sm1 cancers were 12 - 27 %, while in sm2 and sm3 cancers the rates were 36 - 46 % [1]. Based on those findings, m1 and m2 tumors can be considered to be localized and therefore having a good indication for local treatment such as EMR. However, in order to select the most appropriate treatment for superficial cancer, especially about the indication for EMR, it is absolutely essential to have a precise evaluation of the depth of cancer invasion, with particular attention to discrimination between m1 and m2 tumors on the one hand and m3 and sm1 tumors on the other.

Figure 1 Classification of the depth of cancer invasion. ep, epithelium; lpm, lamina propria; mm, muscularis mucosa; sm, submucosa; mp, proper muscle; a, adventitia.

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