Prognostic significance of mature dendritic cells and factors associated with their accumulation in metastatic liver tumors from colorectal cancer

Although dendritic cells (DCs) play an important role in tumor immunity, their prognostic significance and factors related to mature DCs have not been addressed in metastatic liver tumors. In surgically resected, paraffin-embedded tissue sections from 70 patients with colorectal liver metastasis, CD83 (a marker of mature DCs) positive cells and cancer cells positive for the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay were counted. Expression of gp96, which is considered to participate in the maturation of DCs, was also evaluated. CD83-positive cells were observed predominantly in the cancer invasive margin. Patients with CD83-positive cell counts of <2 per field had a significantly poorer prognosis (5-year survival rate 47.5% vs 23.1%; P=0.0184). Patients with >0.83% apoptotic cancer cells had significantly higher numbers of CD83-positive cells (7.3 +/- 7.3 vs 4.0 +/- 5.1; P=0.039). Patients with immunohistochemically positive gp96 expression in tumors had significantly higher numbers of CD83-positive cells than those with negative gp96 expression (6.0 +/- 6.5 vs 1.4 +/- 2.3; P=0.0108). Patients with metachronous occurrence of liver metastasis had significantly higher numbers of CD83 positive cells than those with synchronous detection (6.3 +/- 6.5 vs 3.9 +/- 5.9; P=0.0313). Although the number of apoptotic cancer cells, degree of tumor gp96 expression, and synchronous or metachronous occurrence of liver metastasis did not directly influence patient outcome, they did influence the number of CD83-positive cells in the cancer invasive margin, which was a significant prognostic factor in patients with colorectal liver metastasis.