There was no difference in IRF9 H score between BLBC and non-BLBC (Supplementary Fig. 8h) and analysis of IRF9 expression specifically in the BLBC subtype confirmed that high IRF9 expression was associated with a 2.5 times reduced risk of breast cancer death compared to patients with IRF9-negative tumors (Supplementary Fig. 8i). This evidence concerns the gene IRF9 and breast cancer.