Endoscopic ultrasonography in patients with thyroid cancer: Its usefulness and limitations for evaluating esophagopharyngeal invasion

Background and Study Aims: Although computed tomography (CT) and magnetic resonance imaging (MRI) are useful for detecting esophagopharyngeal invasion by thyroid cancer, they cannot assess the depth of invasion, which is important for the surgical planning. In the present study, endoscopic ultrasonography (EUS) of the esophagus was used to assess esophagopharyngeal invasion by thyroid cancer, and the value of this technique was assessed prospectively. Patients and Methods: Between 1 December 1998 and 31 December 2000, EUS examinations were carried out in 59 patients in whom esophagopharyngeal invasion by thyroid cancer was suspected due to large tumors or tumors with poor mobility. The EUS findings were evaluated in 52 patients (10 men, 42 women; mean age 62.4 years; mean tumor size 39.5 mm) with complete resections, and compared with the pathological results. Results: The diagnostic specificity and accuracy of EUS in assessing invasion into the muscularis propria (82.9%, 82.7%) were greater than those of MRI (60%; P = 0.034, 65.4%; P = 0.044) and esophagography (58.8%; P = 0.034, 60%; P = 0.028). The accuracy for detecting cancer invasion located in the upper part of the lobe was less than for invasion in the middle and/or lower parts of the lobe (P = 0.020). Conclusions. EUS is useful for assessing esophagopharyngeal invasion by thyroid cancer, although its effectiveness may be limited in thyroid lesions located in the upper part of the lobe.