Sentinel Lymph Node Analysis in Patients With Breast Cancer Revealed Alterations in T Cells Subset.

In breast cancer, sentinel lymph nodes (SLNs) represent the first site of interaction between tumor-derived antigens and the host immune system. However, descriptive data on immune cell subsets within the SLN remains limited. This exploratory study evaluated immune cell populations in SLN samples from women with invasive breast cancer (IBC) using flow cytometry, and assessed their distribution according to clinicopathological characteristics. SNL scrapings were collected from 22 patients with IBC. SNL cells were evaluated using flow cytometry, and the results were compared with clinical and pathological variables, such as tumor subtype, axillary status, lymphovascular invasion (LVI), histological grades, and expression of estrogen receptors (ERs) and human epidermal growth factor receptor 2 (HER2). The frequencies of monocytes and neutrophils were not significantly correlated with the clinical variables analyzed. In patients with LVI, there was an increase in the frequency of CD4⁺ T cells and programmed death-1 (PD-1) expression in CD8⁺ T-cells. Furthermore, a reduction in central memory CD4⁺ T cells and an increase in terminal effector memory CD4⁺ T cells were observed in patients with histological grade III disease compared to those with histological grade I disease. It was also observed that in patients expressing ERs and HER2, there was an increase in PD-1 and programmed death-ligand 1 expression in CD8⁺ T-cells. These findings provide a descriptive overview of immune cell distribution in SLNs according to their clinicopathological features. These results are preliminary and hypothesis-generating, supporting the need for larger longitudinal studies to further characterize the immune profiles within tumor-draining lymph nodes.