CDX2 protein distribution in the gastric mucosa in chronic gastritis by a semi-quantitative index and its reproducibility

Abstract

Introduction The Cdx2 gene provides an intestinal differentiation of epithelial cells and plays an oncosupressive role. An indirect method of the Cdx2 gene expression assessment is the immunohistochemical study of its product, the CDX2 protein. Therefore, the common approach to the immunohistochemical study of the CDX2 protein hasn’t been developed yet. A semi-quantitative CDX2 index based on the percentage of CDX2-positive cells in the tissue specimen, the staining intensity and an expression pattern has been proposed.The purpose of the study was to assess the reproducibility of the semi-quantitative CDX2 index calculation in chronic atrophic gastritis stages I-IV.Materials and methods 20 chronic atrophic gastritis cases (5 cases for each stage of the gastritis according to the Operative link for gastritis assessment system) were taken according to the Maastricht V protocol and examined by the immunohistochemical method (CDX2, clone EPR2764Y, ready to use). The reproducibility of the CDX2 semi-quantitative index was assessed by five pathologists. An agreement between observed raters was measured by the kappa statistics.Results The Cohen’s κ value is 0,8 for unweighted κ and 0,97 for weighted κ (extremely high level of agreement) for the semi-quantitative CDX2 index calculation.Discussion The least reproducible parameter used for the semi-quantitative CDX2 index calculation the percentage of CDX2-positive cells because of the subjective assessment. The Cohen’s weighted κ value was higher compared to the unweighted κ because of the close yet not similar CDX2 semi-quantitative index values calculated by pathologists.Conclusion The semi-quantitative CDX2 index can be used to rank CDX2 expression and has a high level of reproducibility.