Prognostic significance of CD8(+) tumor-infiltrating lymphocytes and CD66b(+) tumor-associated neutrophils in the invasive margins of stages I–III colorectal cancer

Tumor-infiltrating immune cells play an essential role in cancer progression and may help supplement the Tumor, Node, Metastasis (TNM) classification for cancer prognosis. Currently, there are numerous conflicting reports discussing the significance of tumor-associated neutrophils (TANs) in colorectal cancer (CRC). In particular, the role of TANs in the invasive margin is unclear. The present study investigated the prognostic significance of CD66(+) TANs and CD8(+) tumor-infiltrating lymphocytes (TILs) in the invasive margin of 103 patients with CRC. By using immunohistochemistry, survival analysis was performed on CD8(+) TILs and CD66(+) TANs individually, as well as models including TILs and TANs simultaneously. The findings indicated that the densities of CD8(+) TILs and CD66b(+) TANs in the invasive margin may provide significant prognostic value for predicting survival. Moreover, the combined evaluation of CD8(+) TILs and CD66b(+) TANs in the invasive margin could further improve the validity for the prediction of oncological outcomes. In addition, multivariate analysis revealed that simultaneous low tumor infiltration by CD8(+) TILs and CD66b(+) was an independent predictive factor for overall survival (HR=4.17, 95% CI, 1.55-12.5; P=0.004) and disease-free survival (HR=2.75, 95% CI, 1.27-6.12; P=0.01). Given the importance of CD8(+) TILs and CD66b(+) TANs in the tumor microenvironment, the assessment of their densities in the invasive margin may serve as a valuable prognostic marker for CRC.