Evaluation of the Role of Tumor-Infiltrating Lymphocytes and CD8+ Cytotoxic Lymphocytes in the Survival of Patients with Breast Cancer.

Background: This study aimed to evaluate the significance of tumor-infiltrating lymphocyte (TIL) and the number of CD8+ T cells in breast cancer and their relationship with the other clinicopathological factors, and overall survival (OS) was investigated. Materials and Methods: The studied samples were breast cancer patients (2005-2017) referring to the medical oncology departments for treatment. Pathologic samples of breast cancer patients were evaluated in terms of TIL and positive immunohistochemical staining for CD8 cytotoxic cells. Results: 299 patients were entered into the study, three were male and 296 female. Their mean follow-up period was 61 months. Statistical findings indicated that lymph involvement is more accompanied by low TIL within the tumor (0.011). Correlations were observed between the estrogen, progesterone receptors, P53 state, and TIL, which were significant by P-value<0.049, P-value=0.024, P-value =0.002, respectively. With any Ki67 value, the number of patients with less than 30% TIL was more considerable than the other two groups with lymphocyte cut-off of 30-50% and more than 50%. Comparison of the OS of patients with positive and negative CD8 cytotoxic lymphocytes in 45 patients with lymphocyte infiltration of equal or more than 40% showed that the OS results were in favor of patients with CD8+ cytotoxic lymphocyte (0.022). Out of 299 patients, 17 died. Conclusion: Our findings showed that in cases of CD8+ cytotoxic lymphocytes in tumors, the OS of the patients will be enhanced which can act as an independent factor.