P53 AND DNA PLOIDY IN BARRETT'S METAPLASIA

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DESCRIPTION: The goal of this study is to determinewhether the accuracy and cost-effectiveness of endoscopic surveillance protocols aimed at detecting early malignant transformation in patients with Barrett's metaplasia (BM) can be improved by: 1) testing the hypothesis that p53 protein accumulation, DNA aneuploidy, and increased G0G1 or G2M fractions are more accurate and objective markers of malignant potential in Barrett's metaplasia (Barrett's esophagus) than the routine morphologic evaluation of dysplasia, 2) determining whether biopsy and cytology combined are more useful than either biopsy or cytology alone, 3) determining the time period that elapses between the appearance of LGD/IND, p53 protein accumulation, and DNA ploidy abnormalities, and between the development of high grade dysplasia (HGD) and adenocarcinoma (CA), and 4) perform cost-analysis to determine whether a surveillance program can be constructed in which biopsy and cytology are utilized in conjunction with p53 and DNA ploidy determination, and is less costly than current surveillance programs. Evaluation of p53 accumulation and DNA ploidy studies will be performed on initial and follow-up biopsies and brush cytology material from at least 200 patients with Barrett's metaplasia (BM). Step sections of biopsies (Bx) will be stained with hematoxylin and eosin, Feulgen stain for DNA quantitation, and immunostained for p53 protein, p53 gene mutational analysis will be performed by direct sequencing on microdissected tissues. Each case will be then analyzed for dysplasia, DNA ploidy patterns by image analysis, and p53 accumulation and gene mutation. Cytologic preparations (Cy) will be also evaluated for dysplasia, DNA ploidy patterns by image analysis, and p53 accumulation. The data will be compiled every two years and correlated with the patients outcome, using the development of HGD and CA as end points in separate analyses, and evaluated by univariate and multivariate analysis. The sensitivity, specificity, and positive and negative predictive value of each of these markers as predictors of HGD and of CA development will be determined separately on markers detected by Bx, Cy, and by the Bx and Cy combined. These will be compared to determine whether the use of both Bx and Cy in the follow-up of patients with BM is better than Bx or Cy alone. The time between the appearance of one of the markers and the development of carcinoma will also be studied, in order to identify a period of time in which close endoscopic surveillance is both clinically warranted and cost-effective. p53 mutations will be compared with p53 protein accumulation, and with DNA ploidy and patient outcome in order to determine if there are specific mutations associated with progression to DNA aneuploidy and CA. A multi step progression model will be constructed, upon which a new surveillance program will be proposed. A cost analysis will be then performed to determine whether a molecular based surveillance program would be more cost-effective than current program which is based on morphologic grading of dysplasia.