Prognostic Value of Immune Cells Subsets Within the Tumor Microenvironment in Patients With Rectal Adenocarcinoma

Background/Aim: One-third of newly diagnosed colorectal cancer cases are rectal cancers. Multimodal treatment regimens including surgery, radiotherapy, and chemotherapy improve local control and survival outcome and decrease tumor relapse for patients with rectal adenocarcinoma (READ). However, stratification of patients to predict their responses is urgently needed to improve therapeutic responses. Patients and Methods: Immunostainings of CD3⁺, CD8⁺, and CD45RO⁺ immune cell subsets within the tumor microenvironment were evaluated using immunohistochemistry in two hundred seventy-nine READ patients. Results: In this study, we found that examination of the adaptive immune response by quantifying CD3⁺, CD8⁺, and CD45RO⁺ immune cell subsets, provides improved and independent prognostic value for patients with READ. Regardless of conventional clinical and pathologic parameters, the densities of T cell subsets were strongly related to a better prognosis in patients with READ. High density of intratumoral immune cells is associated with absence of nodal metastasis, lymphovascular invasion, and perineural invasion. Moreover, high tumor-infiltrating lymphocyte (TIL) subsets were associated with favorable survival outcome in patients with READ, especially high-risk patients with advanced READ. Conclusion: Immune cell subsets including CD3, CD8, and CD45RO within the tumor microenvironment were independent prognostic factors for patients with READ.