Differential cell cycle-regulatory protein expression in biliary tract adenocarcinoma: correlation with anatomic site, pathologic variables, and clinical outcome.

Purpose: Biliary tract adenocarcinomas (BTAs), although anatomically related, arise through ill-defined and possibly different location-related pathogenetic pathways. This clinicopathologic study characterizes differences in cell cycle-regulatory protein expression across the spectrum of BTA.
Methods: Tissue microarrays were prepared from paraffin-embedded surgical specimens with triplicate cores of BTA and benign tissue. Immunohistochemical expression of p53, cyclin D1, p21, Bcl2, p27, Mdm2, and Ki-67 was assessed, and the results were correlated with pathologic variables and survival. Hierarchical clustering was used to partition the data based on protein expression, and then the data were analyzed according to anatomic location.
Results: Tissue from 128 surgical patients (1992 to 2002) was obtained. Tumor sites of origin were intrahepatic cholangiocarcinoma (IH; n = 23), hilar cholangiocarcinoma (Hilar; n = 54), gallbladder (GB; n = 32), and distal bile duct (Distal; n = 19). p27 expression decreased progressively from proximal to distal in the biliary tree and correlated with location-related differences in outcome; cyclin D1 and Bcl2 overexpression also varied according to anatomic site. Aberrant p53 staining and cyclin D1 overexpression were lower in papillary tumors compared with the more common sclerosing tumors. The expression profiles of GB and Hilar were more similar to each other than either was to IH or Distal (86% clustering in the first partition). After an R0 resection, overexpression of Mdm2 (P = .0062) and absent p27 expression (P = .0165) independently predicted poor outcome.
Conclusion: BTAs differentially express cell cycle-regulatory proteins based on tumor location and morphology. Prognostic roles were identified for Mdm2 and p27. Overlap in the pathogenesis of GB and Hilar tumors was suggested.