Early-Stage Luminal B-like Breast Cancer Exhibits a More Immunosuppressive Tumor Microenvironment than Luminal A-like Breast Cancer

Background: Breast cancer is a heterogeneous malignant disease with a varying prognosis and is classified into four molecular subtypes. It remains one of the most prevalent cancers globally, with the tumor microenvironment playing a critical role in disease progression and patient outcomes. Methods: This study evaluated tumor samples from 40 female patients with luminal A and B breast cancer, utilizing flow cytometry to phenotypically characterize the immune cells and tumor cells present within the tumor tissue. Results: The luminal B-like tumor samples exhibited increased infiltration of CD4+ cells, regulatory T cells (Tregs), and Th17 cells and decreased levels of NK cells, γδ T cells, Th1 cells, and follicular T cells, which is indicative of a more immunosuppressive tumor microenvironment. Conclusions: These findings suggest that luminal B-like tumors have a microenvironment that is less supportive of effective anti-tumor immune responses compared to luminal A tumors. This study enhances the understanding of the immunological differences between luminal subtypes of breast cancer and identifies potential new therapeutic targets and biomarkers that could drive advancements in precision medicine for breast cancer management.