Immunohistochemical profiling of liver metastases and matched-pair analysis in patients with metastatic pancreatic ductal adenocarcinoma.

ABSTRACT

BACKGROUND: The purpose of the current study was to investigate the immunohistochemical (IHC) profile of liver metastases (LM) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: Expression of 15 IHC markers in liver biopsies from 77 patients with PDAC, who were diagnosed between 2010 and 2014, were evaluated. In a separate subgroup analysis (n = 12), paired samples (LM and primary tumor) from the same patient were investigated for IHC profile differences. RESULTS: LM samples were classified as pancreatobiliary-type (PB-type) in 72 patients (93.5%), intestinal-type (INT-type) in four patients (5.2%), and squamous in one patient (1.3%). There was no significant difference in overall survival (OS) between LM of the PB-type or INT-type (p = 0.097). In a multivariate analysis, age <70 years (p = 0.047), absence of SMAD4 mutation (p = 0.026), absence of CDX2 expression (p = 0.003), and well to moderate differentiation were significant prognostic factors for better OS in patients with LM (p = 0.031). Analysis of paired tissue samples from LM and the primary tumor revealed a difference in CDX2 (50% increase, p = 0.125) and SMAD4 (33% loss of SMAD4, p = 0.375). CONCLUSIONS: CDX2 expression and SMAD4 mutation indicate a poor outcome in patients with LM of PDAC. Matched-pair analysis revealed differences in distinct IHC marker expression.