Tumor-Infiltrating FOXP3+ T Regulatory Cells Show Strong Prognostic Significance in Colorectal Cancer

Purpose To determine the prognostic significance of FOXP3+ lymphocyte (Treg) density in colorectal cancer compared with conventional histopathologic features and with CD8+ and CD45RO+ lymphocyte densities. Patients and Methods Tissue microarrays and immunohistochemistry were used to assess the densities of CD8+, CD45RO+, and FOXP3+ lymphocytes in tumor tissue and normal colonic mucosa from 967 stage II and stage III colorectal cancers. These were evaluated for associations with histopathologic features and patient survival. Results FOXP3+ Treg density was higher in tumor tissue compared with normal colonic mucosa, whereas CD8+ and CD45RO+ cell densities were lower. FOXP3+ Tregs were not associated with any histopathologic features, with the exception of tumor stage. Multivariate analysis showed that stage, vascular invasion, and FOXP3+ Treg density in normal and tumor tissue were independent prognostic indicators, but not CD8+ and CD45RO+. High FOXP3+ Treg density in normal mucosa was associated with wors...