EUS accuracy is high in defining resectable lesions confined to the esophageal wall (TI, T2) without spread to other sites (see Fig 4). In this regard, EUS is better for staging adenocarcinomas (89-92%) than squamous carcinomas (64-84%) because of the tendency of squamous lesions to have submucosal microscopic lymphangiosis carcinomatosa beyond the tumor margin, detectable only on histological analysis [35,36]. Early tumor stages are generally the best candidates for surgical resection; however, for those carcinomas confined to the mucosa, alternative local treatments, such as strip biopsy, photodynamic therapy, or endoscopic dissection, are alternatives in which EUS may help in directing the most appropriate treatment.

Currently, the combination of CT plus EUS [45] provides very accurate preoperative staging (85% compared with 60% for either method alone for overall stage accuracy). Whether all patients with small lesions will need a CT scan or whether all patients with extensive large lesions need EUS will be determined in prospective studies that assess cost-effectiveness.

Multimodal selective treatment concepts can now be applied on a rational basis. EUS will most accurately identify patients with unresectable tumors who are candidates for preoperative chemotherapy and radiotherapy. Only those patients responding to treatment become candidates for surgery, assuming the patient is not functionally inoperable. Hilgenberg and colleagues [6] reported the best results: 36% 5-year survival when chemotherapy, radiotherapy, and surgery were combined.

The impact on overall patient outcome will clearly improve as selective treatment improves prognosis and quality of life.

For detection of anastomotic recurrences of esophageal carcinomas, EUS has been shown to be sensitive but somewhat nonspecific [45,46]. It is most valuable in those patients in whom recurrence is suspected based on other standard techniques, but in whom endoscopic biopsy is negative, which occurs in approximately 25% of recurrences. For diagnosis of local recurrence of esophageal carcinoma, EUS has a sensitivity of 95%, a specificity of 80%, a positive predictive value of 88%, and a negative predictive value of 92%.

EUS evaluation of lymph nodes due to metastasis from lung carcinomas appears to be useful [47]. Excluding right superior mediastinal lymph nodes, the sensitivity and specificity were 81 and 98%, respectively, in detecting malignancy. When anthracosilicosis is present, results are not nearly as good, and directed biopsy is required to confirm diagnosis.

EUS is also useful for monitoring the response to chemotherapy and radiotherapy. Although it can be difficult to differentiate residual malignancy from fibrosis by EUS, estimation of tumor size, and therefore therapeutic response, can be made. However, the most appropriate use of EUS for patients undergoing treatment needs further evaluation. Radiotherapy induces inflammatory and fibrotic changes that complicate interpretation of EUS [48]. EUS will be uncertain or incorrect in 1 of 3 patients even after waiting 3 months after radiotherapy [33].

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