- Email: [email protected]
Barrett's esophagus and early esophageal cancer
III. EARLY CANCER Barrett’s esophagus and early esophageal cancer
Table 1. Stage grouping of esophageal cancer by TNM classification T
Marcia Irene Canto, MD, MHS
EUS FINE-NEEDLE ASPIRATION AND EARLY ESOPHAGEAL CANCER Staging early esophageal cancer EUS has been shown to be the most accurate radiologic method of staging tumors of the gastrointestinal tract. EUS staging (Table 1) is critical in early esophageal cancer because of the potential impact on therapy. T0 and T1 cancers that do not penetrate deeply into the submucosa can be endoscopically treated with curative intent by using either endoscopic mucosal resection (EMR) or mucosal ablation with photodynamic therapy or argon plasma coagulation. T1 tumors are readily seen as focal thickenings of the mucosa (first and second layers) that may extend into the submucosal layer but not into the muscle layer. The accuracy rate for staging esophageal cancers is lowest for T1 and T2 lesions. Hence, highfrequency catheter miniprobes have been used to improve the staging of early cancers.1 Probes can raise the EUS T-staging accuracy for early squamous cell esophageal cancers from 71% to 92% (71% to 86% for T1 mucosal cancer and 78% to 94% for T1 submucosal cancer).1 However, there are little published data on the EUS staging accuracy in patients with early adenocarcinoma in Barrett’s esophagus. Earlier studies with first- and second-generation standard radial echoendoscopes suggested a low staging accuracy.2,3 However, one later study reported high sensitivity (100%), specificity (94%), and negative predictive value (100%) of preoperative EUS for detection of submucosal invasion.4 Preliminary data from studies with both standard and high-frequency EUS suggest that the presence of layer 3 disruption suggests submucosal invasion, but its absence does not exclude it.5 Indeed, in a Current affiliation: Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Reprint requests: Marcia Irene Canto, MD, MHS, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, 1830 E. Monument St., Room 425, Baltimore, MD 21205. Copyright © 2002 by the American Society for Gastrointestinal Endoscopy 0016-5107/2002/$35.00 + 0 37/0/127752 doi:10.1067/mge.2002.127752 S66
GASTROINTESTINAL ENDOSCOPY
Stage Stage Stage Stage Stage
0 I IIA IIB III
Stage IVA Stage IVB
Tis T1 T2 or T3 T1 or T2 T3 T4 Any T Any T
N N0 N0 N0 N1 N1 Any N Any N Any N
M M0 M0 M0 M0 M0 M0 M1a M1b
large (n = 130) retrospective series from the Mayo Clinic,3 the overall accuracy of EUS T-staging was only 61% (43% for T1 and 70% for T0) because of both overstaging and understaging. The T-staging accuracy was not improved significantly in the 16 patients who were also preoperatively staged with the 20-MHz probe. The risk of lymph node metastasis approaches 40% in deep T1 submucosal esophageal cancers. Hence, EUS N-staging is also important in selecting patients for possible endoscopic curative therapy of early esophageal cancer. When EUS N-staging is compared with results of meticulous operative dissection of lymph nodes, the overall accuracy for staging lymph nodes in esophageal cancer is about 87% to 88%.6 But most patients reported in studies of EUS and esophageal cancer staging have advanced disease. There are little published data on the accuracy of EUS for determining the presence or absence of lymph node involvement in patients with early adenocarcinoma. Mediastinal lymph nodes can be commonly found in patients with Barrett’s esophagus. In one series of patients who had preoperative EUS, the prevalence of malignant, benign, and indeterminate lymph nodes in patients with high-grade dysplasia who had surgery was 0%, 25%, and 12%, respectively.7 Limited data suggest that the EUS accuracy for detecting malignant lymphadenopathy or excluding it is high. One small published study showed that preoperative EUS detected the single instance of lymph node metastasis in 1 of 17 patients (this patient had a T3 N1 cancer) but inaccurately predicted the presence of N1 disease in 4 patients.4 Hence, the specificity of EUS was 81% and the sensitivity was 100%. Our prospective data from Johns Hopkins support these findings.7 In 27 patients who had Barrett’s esophagus with highgrade dysplasia or early adenocarcinoma who had preoperative EUS, prevalence of malignant lymphVOLUME 56, NO. 4 (SUPPL), 2002
Barrett’s esophagus and early esophageal cancer
adenopathy was 3.7% (1 patient with a T1 N1 submucosal cancer correctly staged by EUS).7 Hence, for detection of malignant lymph nodes, standard EUS had a sensitivity, specificity, positive predictive value, and negative predictive value, and overall accuracy of 100%, 88%, 25%, 100%, and 89%.7 Preliminary results from a retrospective study by investigators from the Mayo Clinic showed a similar overall accuracy rate of 88%8 but the sensitivity, specificity, and negative predictive value were not reported. Hence, the sensitivity and negative predictive value of EUS may be high enough such that endoscopic therapy may be considered in suitable patients if malignant lymph nodes are absent at EUS. Long-term follow-up studies are needed in patients who undergo EUS before endoscopic curative therapy. EUS has a potentially large clinical impact in patients with early esophageal cancer and in patients with Barrett’s esophagus with high-grade dysplasia. In our experience,7 EUS lymph node staging results were associated with a change in management plan in 10% of patients with Barrett’s esophagus and high-grade dysplasia and 40% of Barrett’s adenocarcinoma patients (p = 0.01); it led to chemoradiation therapy (n = 3), change in plan for endoscopic therapy (n = 4), and/or change in plan for surgery (n = 7).7 EUS cannot accurately discriminate between malignant and benign/inflammatory lymphadenopathy. EUS-guided fine-needle aspiration (FNA) is expected to increase staging accuracy by differentiation of malignant from benign lymphadenopathy. EUS-guided FNA can upstage T1 tumors of the esophagus (stage I to IIb, Table 1) and lead to a decision to administer preoperative adjuvant chemoradiation therapy. The overall accuracy of EUS-guided FNA and of EUS-guided FNA of lymph nodes is 82% and 91%, respectively, when compared with surgery.9,10 EUSguided FNA of a lymph node is most helpful when positive (positive predictive value 100%),11 but the chance of a falsely negative FNA is about 20%. The performance characteristics of EUS-FNA may be very different if one considers only early esophageal cancers, in which prevalence of regional lymph node metastasis is lower. EUS-FNA can also be problematic for the cytopathologist in patients with long Barrett’s esophagus and indeterminate or malignant-appearing lymph nodes; passage of the needle through Barrett’s mucosa with high-grade dysplasia or occult carcinoma may lead to false diagnosis of a malignant lymph node because of contamination by epithelial cells. Hence, consider EUSFNA only if the esophageal wall at the level of the lymph node is lined by normal squamous mucosa. VOLUME 56, NO. 4 (SUPPL), 2002
M Canto
Detection of early recurrent or residual esophageal cancer In a recently presented prospective study of 51 Japanese patients evaluated by high-frequency EUS probes (20 MHz, 30 MHz) after endoscopic mucosal resection or chemoradiation therapy,12 7 cases of residual or early recurrent esophageal cancer (submucosal) were detected in the lamina propria by EUS and confirmed by endoscopic biopsy or needle aspiration. In 5 of these 7 cases, malignancy was proven and additional treatments were performed. These preliminary results suggest the possibility of early diagnosis of endoscopically inapparent small residual or early recurrent esophageal cancers after mucosal resection or nonoperative therapy. EUS AND BARRETT’S ESOPHAGUS The role of EUS in screening for esophageal cancer is limited. EUS is not generally recommended as part of screening or surveillance procedures. Limited published data suggest that there may be a future role for EUS in certain high-risk patients with Barrett’s esophagus. Preliminary reports suggest that EUS has a potential for detecting cancer in patients with Barrett’s esophagus when endoscopy does not, particularly when performed in carefully selected patients with dysphagia, focal nodule or stricture, and with only high-grade dysplasia in biopsies.5,13 Patients with a stricture or nodule have an increased likelihood of submucosal invasion.4 When superficial cancer is present, it may appear as focal thickening located in the first 2 or 3 layers. The presence of an early adenocarcinoma in Barrett’s esophagus is suggested particularly when there is disruption of layer 3, suggesting submucosal invasion.5 When performed in Barrett’s esophagus patients with high-grade dysplasia and no cancer in endoscopic biopsies, high-frequency catheter EUS (20 MHz) may demonstrate focal thickening or wall irregularity of layer 2 with or without disruption of layer 3.14 The specificity of standard and highfrequency EUS (for excluding an occult adenocarcinoma) in one small series is very high (100%: 95% CI [89%, 100%]).14 It is therefore reasonable to perform EUS in patients with Barrett’s esophagus with high-grade dysplasia because of the risk for adenocarcinoma, which in turn, can be detected and staged at the same procedure. The diagnostic yield for EUS in these patients is small, particularly when there is no visible endoscopic lesion. In summary, the role of EUS in early esophageal cancer continues to expand with improved EUS instrumentation and increased experience. Its role in Barrett’s esophagus is limited to the diagnosis and staging of occult adenocarcinoma in patients wit highGASTROINTESTINAL ENDOSCOPY
S67
K Yasuda
EUS in the detection of early gastric cancer
grade dysplasia (particularly those with a lesion). Future studies of EUS-FNA in early esophageal adenocarcinoma and occult residual or early recurrent disease are indicated, and these may potentially expand the applications of EUS in our day-to-day practice. REFERENCES 1. Hasegawa N, Niwa Y, Arisawa T, Hase S, Goto H, Hayakawa T. Preoperative staging of superficial carcinoma: comparison of a standard probe and standard endoscopic ultrasonography. Gastrointest Endosc 1996;44:388-93. 2. Falk GW, Catalano MF, Sivak MV Jr, Rice TW, Van Dam J. Endosonography in the evaluation of patients with Barrett’s esophagus and high-grade dysplasia. Gastrointest Endosc 1994;40:207-12. 3. Wang K, Norbash A, Geller A, DiMagno E. Endoscopic ultrasonography in the assessment of Barrett’s esophagus with high grade dysplasia or carcinoma [abstract]. Gastroenterology 1996;110:A611. 4. Scotiniotis IA, Kochman ML, Lewis JD, Furth EE, Rosato EF, Ginsberg GG. Accuracy of EUS in the evaluation of Barrett’s esophagus and high-grade dysplasia or intramucosal carcinoma. Gastrointest Endosc 2001;54:689-96. 5. Parent J, Levine DS, Haggitt RC, Wood DE, Reid BJ, Kimmey MB. Accuracy of endoscopic ultrasound staging in patients with Barrett’s esophagus and intramucosal carcinoma [abstract]. Gastrointest Endosc 1997;45:AB76. 6. Botet JF, Lightdale CJ, Zauber AG, Gerdes H, Urmacher C, Brennan MF. Preoperative staging of esophageal cancer: comparison of endoscopic US and dynamic CT. Radiology 1991;181:419-25.
S68
GASTROINTESTINAL ENDOSCOPY
7. Canto MIF, Cruz-Correa MR, Heitmiller RF, Kantsevoy RF, Kalloo AN. What is the accuracy of EUS lymph node staging in patients with Barrett’s esophagus and high grade dysplasia or early cancer? A prospective study with implications for endoscopic therapy [abstract]. Gastrointest Endosc 2001;53: AB171. 8. Buttar N, Wang K, Lutzke L, Krishnadath K. The use of endoscopic ultrasonography in Barrett’s esophagus [abstract]. Gastrointest Endosc 2001;53:AB172. 9. Wiersema MJ, Vilmann P, Giovannini M, Chang KJ, Wiersema LM. Endosonography-guided fine-needle aspiration biopsy: diagnostic accuracy and complication assessment. Gastroenterology 1997;112:1087-95. 10. Binmoeller KF, Seifert H, Soehendra N. Endoscopic ultrasonography-guided fine-needle aspiration biopsy of lymph nodes. Endoscopy 1994;26:780-3. 11. Wiersema MJ, Wiersema LM, Khusro Q, Cramer HM, Tao LC. Combined endosonography and fine-needle aspiration cytology in the evaluation of gastrointestinal lesions. Gastrointest Endosc 1994;40:199-206. 12. Murata Y, Ohta M, Hayashi K, Takayama Y, Ohi I. The role of EUS in early detection of a residual or recurrent mass after treatment of superficial esophageal cancer [abstract]. Gastrointest Endosc 2002;55:AB227. 13. Stotland B, Kochman M, Smith D, Rosato E, Furth E, Ginsberg G. Endosonography is indicated for selected patients with Barrett’s esophagus [abstract]. Gastrointest Endosc 1997;45:AB181. 14. Parent J, Levine D, Haggitt R, Reid B, Kimmey M. Role of endoscopic ultrasound in patients with Barrett’s esophagus and high grade dysplasia [abstract]. Gastrointest Endosc 1997;45:AB76.
VOLUME 56, NO. 4 (SUPPL), 2002
Table 1. Stage grouping of esophageal cancer by TNM classification T
Marcia Irene Canto, MD, MHS
EUS FINE-NEEDLE ASPIRATION AND EARLY ESOPHAGEAL CANCER Staging early esophageal cancer EUS has been shown to be the most accurate radiologic method of staging tumors of the gastrointestinal tract. EUS staging (Table 1) is critical in early esophageal cancer because of the potential impact on therapy. T0 and T1 cancers that do not penetrate deeply into the submucosa can be endoscopically treated with curative intent by using either endoscopic mucosal resection (EMR) or mucosal ablation with photodynamic therapy or argon plasma coagulation. T1 tumors are readily seen as focal thickenings of the mucosa (first and second layers) that may extend into the submucosal layer but not into the muscle layer. The accuracy rate for staging esophageal cancers is lowest for T1 and T2 lesions. Hence, highfrequency catheter miniprobes have been used to improve the staging of early cancers.1 Probes can raise the EUS T-staging accuracy for early squamous cell esophageal cancers from 71% to 92% (71% to 86% for T1 mucosal cancer and 78% to 94% for T1 submucosal cancer).1 However, there are little published data on the EUS staging accuracy in patients with early adenocarcinoma in Barrett’s esophagus. Earlier studies with first- and second-generation standard radial echoendoscopes suggested a low staging accuracy.2,3 However, one later study reported high sensitivity (100%), specificity (94%), and negative predictive value (100%) of preoperative EUS for detection of submucosal invasion.4 Preliminary data from studies with both standard and high-frequency EUS suggest that the presence of layer 3 disruption suggests submucosal invasion, but its absence does not exclude it.5 Indeed, in a Current affiliation: Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Reprint requests: Marcia Irene Canto, MD, MHS, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, 1830 E. Monument St., Room 425, Baltimore, MD 21205. Copyright © 2002 by the American Society for Gastrointestinal Endoscopy 0016-5107/2002/$35.00 + 0 37/0/127752 doi:10.1067/mge.2002.127752 S66
GASTROINTESTINAL ENDOSCOPY
Stage Stage Stage Stage Stage
0 I IIA IIB III
Stage IVA Stage IVB
Tis T1 T2 or T3 T1 or T2 T3 T4 Any T Any T
N N0 N0 N0 N1 N1 Any N Any N Any N
M M0 M0 M0 M0 M0 M0 M1a M1b
large (n = 130) retrospective series from the Mayo Clinic,3 the overall accuracy of EUS T-staging was only 61% (43% for T1 and 70% for T0) because of both overstaging and understaging. The T-staging accuracy was not improved significantly in the 16 patients who were also preoperatively staged with the 20-MHz probe. The risk of lymph node metastasis approaches 40% in deep T1 submucosal esophageal cancers. Hence, EUS N-staging is also important in selecting patients for possible endoscopic curative therapy of early esophageal cancer. When EUS N-staging is compared with results of meticulous operative dissection of lymph nodes, the overall accuracy for staging lymph nodes in esophageal cancer is about 87% to 88%.6 But most patients reported in studies of EUS and esophageal cancer staging have advanced disease. There are little published data on the accuracy of EUS for determining the presence or absence of lymph node involvement in patients with early adenocarcinoma. Mediastinal lymph nodes can be commonly found in patients with Barrett’s esophagus. In one series of patients who had preoperative EUS, the prevalence of malignant, benign, and indeterminate lymph nodes in patients with high-grade dysplasia who had surgery was 0%, 25%, and 12%, respectively.7 Limited data suggest that the EUS accuracy for detecting malignant lymphadenopathy or excluding it is high. One small published study showed that preoperative EUS detected the single instance of lymph node metastasis in 1 of 17 patients (this patient had a T3 N1 cancer) but inaccurately predicted the presence of N1 disease in 4 patients.4 Hence, the specificity of EUS was 81% and the sensitivity was 100%. Our prospective data from Johns Hopkins support these findings.7 In 27 patients who had Barrett’s esophagus with highgrade dysplasia or early adenocarcinoma who had preoperative EUS, prevalence of malignant lymphVOLUME 56, NO. 4 (SUPPL), 2002
Barrett’s esophagus and early esophageal cancer
adenopathy was 3.7% (1 patient with a T1 N1 submucosal cancer correctly staged by EUS).7 Hence, for detection of malignant lymph nodes, standard EUS had a sensitivity, specificity, positive predictive value, and negative predictive value, and overall accuracy of 100%, 88%, 25%, 100%, and 89%.7 Preliminary results from a retrospective study by investigators from the Mayo Clinic showed a similar overall accuracy rate of 88%8 but the sensitivity, specificity, and negative predictive value were not reported. Hence, the sensitivity and negative predictive value of EUS may be high enough such that endoscopic therapy may be considered in suitable patients if malignant lymph nodes are absent at EUS. Long-term follow-up studies are needed in patients who undergo EUS before endoscopic curative therapy. EUS has a potentially large clinical impact in patients with early esophageal cancer and in patients with Barrett’s esophagus with high-grade dysplasia. In our experience,7 EUS lymph node staging results were associated with a change in management plan in 10% of patients with Barrett’s esophagus and high-grade dysplasia and 40% of Barrett’s adenocarcinoma patients (p = 0.01); it led to chemoradiation therapy (n = 3), change in plan for endoscopic therapy (n = 4), and/or change in plan for surgery (n = 7).7 EUS cannot accurately discriminate between malignant and benign/inflammatory lymphadenopathy. EUS-guided fine-needle aspiration (FNA) is expected to increase staging accuracy by differentiation of malignant from benign lymphadenopathy. EUS-guided FNA can upstage T1 tumors of the esophagus (stage I to IIb, Table 1) and lead to a decision to administer preoperative adjuvant chemoradiation therapy. The overall accuracy of EUS-guided FNA and of EUS-guided FNA of lymph nodes is 82% and 91%, respectively, when compared with surgery.9,10 EUSguided FNA of a lymph node is most helpful when positive (positive predictive value 100%),11 but the chance of a falsely negative FNA is about 20%. The performance characteristics of EUS-FNA may be very different if one considers only early esophageal cancers, in which prevalence of regional lymph node metastasis is lower. EUS-FNA can also be problematic for the cytopathologist in patients with long Barrett’s esophagus and indeterminate or malignant-appearing lymph nodes; passage of the needle through Barrett’s mucosa with high-grade dysplasia or occult carcinoma may lead to false diagnosis of a malignant lymph node because of contamination by epithelial cells. Hence, consider EUSFNA only if the esophageal wall at the level of the lymph node is lined by normal squamous mucosa. VOLUME 56, NO. 4 (SUPPL), 2002
M Canto
Detection of early recurrent or residual esophageal cancer In a recently presented prospective study of 51 Japanese patients evaluated by high-frequency EUS probes (20 MHz, 30 MHz) after endoscopic mucosal resection or chemoradiation therapy,12 7 cases of residual or early recurrent esophageal cancer (submucosal) were detected in the lamina propria by EUS and confirmed by endoscopic biopsy or needle aspiration. In 5 of these 7 cases, malignancy was proven and additional treatments were performed. These preliminary results suggest the possibility of early diagnosis of endoscopically inapparent small residual or early recurrent esophageal cancers after mucosal resection or nonoperative therapy. EUS AND BARRETT’S ESOPHAGUS The role of EUS in screening for esophageal cancer is limited. EUS is not generally recommended as part of screening or surveillance procedures. Limited published data suggest that there may be a future role for EUS in certain high-risk patients with Barrett’s esophagus. Preliminary reports suggest that EUS has a potential for detecting cancer in patients with Barrett’s esophagus when endoscopy does not, particularly when performed in carefully selected patients with dysphagia, focal nodule or stricture, and with only high-grade dysplasia in biopsies.5,13 Patients with a stricture or nodule have an increased likelihood of submucosal invasion.4 When superficial cancer is present, it may appear as focal thickening located in the first 2 or 3 layers. The presence of an early adenocarcinoma in Barrett’s esophagus is suggested particularly when there is disruption of layer 3, suggesting submucosal invasion.5 When performed in Barrett’s esophagus patients with high-grade dysplasia and no cancer in endoscopic biopsies, high-frequency catheter EUS (20 MHz) may demonstrate focal thickening or wall irregularity of layer 2 with or without disruption of layer 3.14 The specificity of standard and highfrequency EUS (for excluding an occult adenocarcinoma) in one small series is very high (100%: 95% CI [89%, 100%]).14 It is therefore reasonable to perform EUS in patients with Barrett’s esophagus with high-grade dysplasia because of the risk for adenocarcinoma, which in turn, can be detected and staged at the same procedure. The diagnostic yield for EUS in these patients is small, particularly when there is no visible endoscopic lesion. In summary, the role of EUS in early esophageal cancer continues to expand with improved EUS instrumentation and increased experience. Its role in Barrett’s esophagus is limited to the diagnosis and staging of occult adenocarcinoma in patients wit highGASTROINTESTINAL ENDOSCOPY
S67
K Yasuda
EUS in the detection of early gastric cancer
grade dysplasia (particularly those with a lesion). Future studies of EUS-FNA in early esophageal adenocarcinoma and occult residual or early recurrent disease are indicated, and these may potentially expand the applications of EUS in our day-to-day practice. REFERENCES 1. Hasegawa N, Niwa Y, Arisawa T, Hase S, Goto H, Hayakawa T. Preoperative staging of superficial carcinoma: comparison of a standard probe and standard endoscopic ultrasonography. Gastrointest Endosc 1996;44:388-93. 2. Falk GW, Catalano MF, Sivak MV Jr, Rice TW, Van Dam J. Endosonography in the evaluation of patients with Barrett’s esophagus and high-grade dysplasia. Gastrointest Endosc 1994;40:207-12. 3. Wang K, Norbash A, Geller A, DiMagno E. Endoscopic ultrasonography in the assessment of Barrett’s esophagus with high grade dysplasia or carcinoma [abstract]. Gastroenterology 1996;110:A611. 4. Scotiniotis IA, Kochman ML, Lewis JD, Furth EE, Rosato EF, Ginsberg GG. Accuracy of EUS in the evaluation of Barrett’s esophagus and high-grade dysplasia or intramucosal carcinoma. Gastrointest Endosc 2001;54:689-96. 5. Parent J, Levine DS, Haggitt RC, Wood DE, Reid BJ, Kimmey MB. Accuracy of endoscopic ultrasound staging in patients with Barrett’s esophagus and intramucosal carcinoma [abstract]. Gastrointest Endosc 1997;45:AB76. 6. Botet JF, Lightdale CJ, Zauber AG, Gerdes H, Urmacher C, Brennan MF. Preoperative staging of esophageal cancer: comparison of endoscopic US and dynamic CT. Radiology 1991;181:419-25.
S68
GASTROINTESTINAL ENDOSCOPY
7. Canto MIF, Cruz-Correa MR, Heitmiller RF, Kantsevoy RF, Kalloo AN. What is the accuracy of EUS lymph node staging in patients with Barrett’s esophagus and high grade dysplasia or early cancer? A prospective study with implications for endoscopic therapy [abstract]. Gastrointest Endosc 2001;53: AB171. 8. Buttar N, Wang K, Lutzke L, Krishnadath K. The use of endoscopic ultrasonography in Barrett’s esophagus [abstract]. Gastrointest Endosc 2001;53:AB172. 9. Wiersema MJ, Vilmann P, Giovannini M, Chang KJ, Wiersema LM. Endosonography-guided fine-needle aspiration biopsy: diagnostic accuracy and complication assessment. Gastroenterology 1997;112:1087-95. 10. Binmoeller KF, Seifert H, Soehendra N. Endoscopic ultrasonography-guided fine-needle aspiration biopsy of lymph nodes. Endoscopy 1994;26:780-3. 11. Wiersema MJ, Wiersema LM, Khusro Q, Cramer HM, Tao LC. Combined endosonography and fine-needle aspiration cytology in the evaluation of gastrointestinal lesions. Gastrointest Endosc 1994;40:199-206. 12. Murata Y, Ohta M, Hayashi K, Takayama Y, Ohi I. The role of EUS in early detection of a residual or recurrent mass after treatment of superficial esophageal cancer [abstract]. Gastrointest Endosc 2002;55:AB227. 13. Stotland B, Kochman M, Smith D, Rosato E, Furth E, Ginsberg G. Endosonography is indicated for selected patients with Barrett’s esophagus [abstract]. Gastrointest Endosc 1997;45:AB181. 14. Parent J, Levine D, Haggitt R, Reid B, Kimmey M. Role of endoscopic ultrasound in patients with Barrett’s esophagus and high grade dysplasia [abstract]. Gastrointest Endosc 1997;45:AB76.
VOLUME 56, NO. 4 (SUPPL), 2002