CDX2 Expression and Previously Undescribed CDX1 Expression in Primary Gastrointestinal and Metastatic Carcinoid Tumors: An Immunohistochemical Study of 43 Cases
Raveena Reddy, Richard Iverson, Bradley Brimhall, Steve Bigler, Xinchun Zhou, Zelda He, Lafarra Young-Gaylor. University of Mississippi Medical Center, Jackson, MS
Background: CDX1 and CDX2 are homeobox genes which encode for transcription factors essential for intestinal organogenesis. CDX2 has been demonstrated in gastrointestinal (GI) carcinoid tumors whereas CDX1 has never been tested. The aim of this study was to evaluate the expression of CDX1 in GI carcinoid tumors, the relative site-specificity of CDX1 and CDX2, and to determine their patterns of expression in both paired and unpaired analyses of primary carcinoid tumors and metastases.
Design: Immunohistochemical study of CDX1 and CDX2 transcription factors was performed on tissue microarrays from 32 archival tumor samples and on recuts from 11 archival paraffin embedded tissue sections of primary gastrointestinal (GI) carcinoids and extra-gastrointestinal (EGI) tract metastases from the years 1990-2011. Specimens were categorized as either primary tumors or metastases and also by anatomic location as foregut, midgut, hindgut, or EGI. The Fisher Exact test was employed to determine the statistical significance of differences in the proportion of positive immunoperoxidase staining between members of each category.
Results: The proportion of specimens staining positively was higher in metastases compared to primary tumor for both CDX1 (55% vs. 41%) and CDX2 (76% vs. 69%). Neither of these differences achieved statistical significance. The percentage of positively staining specimens differed for each marker depending on the anatomic location.
|Site of tumors||CDX1 (%)||CDX2 (%)|