The density of CD8+ T cells in the total analyzed area including total, tumor nest, and/or stromal compartment was significantly higher in medullary carcinoma of the breast (MCB) than in invasive ductal carcinoma (IDC), while IDC displayed a lower CD8+ T cell density than normal breast tissues, consistent with the hypothesis that MCB has a favorable prognosis with superior CD8+ T cell infiltration (35). Here, CD8A is linked to invasive ductal breast carcinoma.