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Transforming growth factor-alpha, epidermal growth factor receptor, and MiB-1 expression in Barrett's-associated
Abstract:
Overexpression of transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) occurs in Barrett's esophagus, particularly the specialized type, which is at an increased risk for malignant transformation. We performed this study to evaluate the immunohistochemical expression and prognostic significance of these growth factors, as well as MiB-1, the Ki-67 proliferation-associated nuclear antigen, in Barrett's-associated neoplasia. Monoclonal antibodies for TGF-alpha, EGFR, and MiB-1 were evaluated in 25 cases of Barrett's-associated adenocarcinoma (BAA) and in adjacent areas of Barrett's metaplasia and dysplasia. The data were correlated with the pathologic features (grade, stage, depth of invasion, lymph node metastasis) and the clinical outcome of the patients. Of the BAAs, 100% and 64% were positive for TGF-alpha and EGFR, respectively. TGF-alpha and EGFR expression did not correlate with any of the pathologic features of the tumors. By univariate analysis, a higher degree of EGFR immunostaining was significantly associated with poorer patient survival (P = 0.004). After stratified analysis, however, EGFR expression correlated with poor survival only in patients with pathologic Stage II cancer (P = 0.03). There was significant (P < 0.001) increase in the MiB-1 proliferation index (PI) associated with neoplastic progression: Barrett's metaplasia, 22.0% +/- 6.4; dysplasia, 56.5% +/- 21.6; and BAA, 70.0% +/- 17.7. In a separate comparison of the luminal (upper half) and basal (lower half) crypt MiB-1 PI, dysplastic epithelium revealed a significant increase in the luminal crypt MiB-1 PI in comparison with Barrett's metaplastic epithelium (50.7 +/- 24.6 versus 1.2 +/- 1.9, P < 0.001). EGFR expression might have prognostic value for patients with BAA, particularly those with Stage II cancer. The MiB-1 PI pattern supports the metaplasia-dysplasia-adenocarcinoma pathogenetic sequence in these tumors. Furthermore, the pattern of MiB-1 immunostaining might help to distinguish dysplastic from regenerative metaplastic epithelium of Barrett's esophagus in uncertain cases.