Expression of T cell-related proteins in breast ductal carcinoma in situ.

This study aims to explore the expression of T cell subtype markers within the immune cells constituting the tumor microenvironment of ductal carcinoma in situ (DCIS) and to assess its implications. A tissue microarray comprising 191 cases of breast DCIS was created, and immunohistochemistry staining for T cell subtype markers (STAT3, STAT4, STAT-6, and FOXP3) was conducted. The DCIS cases were categorized into luminal, HER-2, and TNBC (Triple-negative breast cancer) types based on ER, PR, HER-2, and Ki-67 results. Additionally, they were classified as low-TIL (tumor-infiltrating lymphocytes) (<10%) or high-TIL (≥10%) types according to stromal TIL. Results revealed that 54.6% were luminal, 39.5% HER-2, and 5.9% TNBC. STAT3 exhibited a high positivity rate in luminal-type tumor cells, while STAT3, STAT4, STAT6, and FOXP3 showed elevated positivity rates in TNBC immune cells (