Difficulty in determining the depth of cancer invasion by EUS for wide-spreading superficial squamous cell cancer of the esophagus

[Aims] The depth of invasion of squamous cell carcinoma of the esophagus (SCCE) is very important because it is highly related to the incidence of lymph node metastasis and patient prognosis. EUS is known to be useful to determine the depth of cancer and staging in SCCE. Wide-spreading superficial SCCE is defined as mucosal and/or submucosal cancer larger than 5cm without an apparent elevated or depressed area in the lesion. This type of SCCE is known to be difficult both in detection and in determining the depth of cancer by radiological and endoscopic examinations. We report EUS findings of three cases. [Patients and methods] All the patients were male with their age ranging from 61 to 75 years. The lesions were found by endoscopy (EGD). EUS (EU-M30 and miniature probe 20 and/or 30MHz, Olympus, Tokyo, Japan) was applied. [Results] The maximum lengths of the lesions were 5 to 10cm. Endoscopic findings at detection included abnormal vascular patterns and slight changes of the surface. Iodine staining clearly showed the cancerous lesions. On EUS, no abnormalities were found in two cases where cancerous lesions could not be visualized because of the thin cancerous layer. In one case, EUS showed a thickened low echoic cancer area mostly limited to mucosal layer and a tiny low echoic area in the fifth layer of 9 layer structure, suggesting a submucosal involvement. Two cases received subtotal esophagectomy, and one of these showed a histological submucosal cancer invasion (178 micro-meter in depth) with lymph node metastases. In the other case, the cancer was limited to the shallow mucosal layer without lymph node metastasis. The other patient received radio-chemotherapy. [Conclusions] In wide-spreading superficial SCCE, determination of the depth of cancer invasion is still difficult even using EUS because the lesion is too wide to observe the whole cancerous area.