Numerous studies have shown that neither CT nor magnetic resonance imaging (MRI) are reliable for differentiating stage I from stage II or even stage III disease. CT staging of tumor depth and invasion based on contour changes and wall thickness is frequently incorrect, especially for early stage disease [38,39]. The extent of local disease (including spread to regional lymph nodes) can only be reliably determined using EUS. In addition, compared with CT, EUS has proven to be more reliable in defining T4 tumor invasion of regional structures, such as aorta or carina, which make a tumor unresectable. Radiotherapy of a tumor that invades the trachea or bronchus is not recommended because of the possibility of development of an esophagotracheal fistula.

Studies that correlate accuracy of EUS and CT to T stage (Table 6) show that EUS is consistently more accurate; most EUS errors (73%) occur in overstaging of T2 lesions (Fig 4). Inflammatory changes can make a lesion invading the muscularis propria (T2) appear as if it just breaks through into adventitia (a T3 lesion). Data on CT scans show it is significantly more accurate for T3 lesions than for other T stages. However, because the 74% level of CT accuracy is due to higher specificity rather than sensitivity, and because EUS is more accurate even for T3 lesions, CT for T-stage disease is not clinically effective. In addition, CT scans are not particularly useful to evaluate N stage. EUS is quite sensitive in finding lymph nodes; however, because these lymph nodes may be inflammatory, an accuracy of only 60% for stage NO lesions is due to overstaging inflammatory lymph nodes as malignant. The accuracy of 70% for CT of NO lesions is due to the fact that CT misses all of these inflammatory nodes, so there can be no confusion in interpretation However, CT similarly misses many small malignant lymph nodes picked up by EUS, resulting in an accuracy of only 48% for CT scan as compared with 87% for EUS in evaluating N1 and N2 disease.

Table 6
Accuracy of Local Staging for Esophageal Carcinoma: EUS Compared with CT

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