Esophagus

Malignant Diseases

Because most tumors of the esophagus involve at least some part of the superficial mucosal layers, endoscopic biopsy and brush cytology are the primary methods for diagnosis. EUS will have a role in diagnosis of those unusual lesions that are only submucosal. However, histology is still required; the role of EUS is to define the area to be biopsied with special deep submucosal biopsy needles [26-29]. Although standard fiberoptic endoscopy allows direct visualization and biopsy of an esophageal lesion, it is not accurate for assessing tumor depth and extent [30]. With EUS, not only the lesion's surface, but also the size, shape, and extension of the primary tumor can be directly visualized in relation to extra-esophageal mediastinal structures and organs, as well as the presence of abnormal appearing lymph nodes.

For esophageal neoplasms, the accuracy [15,30-37] of EUS in assessing T, N, and M stage is 85, 80, and 70%, respectively (see Table 2). There is a significant learning curve. In 1 study, accuracy of T-stage evaluation improved from 59% for the first 30 patients to 81% for more than 30 patients [31]. This finding is supported by the lower median accuracy of 81 % for T staging in studies reporting on less than 35 patients compared with 89% accuracy for those reporting on more than 45 patients [15]. A similar learning curve does not appear to be present for evaluation of lymph nodes, which suggests that criteria of malignant lymph nodes are easier to recognize even though these criteria (see Table 3) are unable to differentiate benign from malignant lymph nodes in approximately 20% of patients. Continuing evolution of EUS criteria for malignant lymph nodes may improve EUS accuracy.

The high accuracy of EUS for local staging (T,N) has allowed major progress toward accurate preoperative TNM staging of esophageal carcinomas. Many studies have shown accuracy to have improved from less than 55% for CT to more than 80% for EUS staging. In terms of patient outcome, the most dramatic impact of EUS may be its highly accurate T staging. Data show that both prognosis and incidence of lymph node metastasis [15,32-37] correlate to the T stages, T1 to T4 (Tables 4, 5).

Table 2
Accuracy of GI Tumor Staging and Respectability with EUS and CT^a

		EUS	CT
Esophagus
	T stage	85	60
	N stage	80	55
	M stage	70	85
	Resectability	80	55
Gastric
	T stage	80	40
	N stage	75	50
	M stage	90	80
	Resectability	85	55
Pancreas
	T stage	90	50
	N stage	75	50
	M stage	75	75
	Resectability	85	55
Biliary System
	T stage	85	45
	N stage	60	50
	M stage	85	85
	Resectability	80	60
Rectum
	T stage	85	70
	N stage	80	55
	M stage	…	75

^a Values are median estimates in percent from references in text.

Table 3
Criteria to Differentiate Malignant and Inflammatory Lymph Nodes

^a Criteria are useful only for frequency of 7.0 MHz or greater.

Table 4
Correlation of EUS T and N Stage to survival for Esophageal Carcinoma

^a Criteria are useful only for frequency of 7.0 MHz or greater.

Table 5
Correlation of EUS T Stage with the Presence of Malignant Lymph Nodes ^a

^a Values are median estimates in percent from references in text.

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