Immunologic profiling of colorectal cancer (CRC) may help to predict the tumors metastatic potential and patients with an aggressive tumor, although not yet metastasized at time of surgery might benefit from adjuvant therapy. In this study we evaluated the prognostic significance of FOXP3(+) T regulatory cells (Tregs), CD3(+) and CD8(+) lymphocyte densities and conventional histopathologic features in nodal negative (n = 820, UICC stage II) CRC. Immunohistochemical studies showed that high expression of FOXP3(+) Tregs is significantly linked to a better clinical outcome (P = 0.0001). In multivariate analysis including tumor stage, tumor grade, type of tumor invasion margin (pushing vs. infiltrating type), lymphovascular invasion (absent vs. present), CD3(+), CD8(+) and FOXP3(+) Tregs expression, only low tumor stage, absence of lymphovascular invasion and high Foxp3 Tregs density showed prognostic significance (P = 0.0132, P = 0.0022 AND P = 0.0234, respectively). Our findings argue towards a clinical utility of FOXP3(+) Tregs immunostaining as an independent good prognostic biomarker in stage II colorectal cancers. FOXP3(+) Tregs immunoscoring, assessment of tumor stage and lymphovascular invasion may help to define stage II cancers with a potentially aggressive behavior and CRC patients who might benefit from adjuvant therapy. A two-scale immunosore related to the median count of FOXP3(+) Tregs proved to be easy and quick to perform.
