Treg infiltration was found to be significantly correlated to patients' age, estrogen receptor status, progesterone receptor status, histological type, and chemotherapy; as well as various immune cell abundance and gene expression (Figures S1–, S3).DEG between Treghigh and Treglow groups were significantly enriched in estrogen and interferon‐gamma response, and IL6_JAK_STAT3 and IL2_STAT5 signaling in the Hallmark gene set (Figure 2F); primary immunodeficiency, T cell, B cell receptor signaling, leukocyte transendothelial migration, et al. Here, PGR is linked to inborn error of immunity.