TP53 and breast cancer: The frequency of TP53 mutation varies according to molecular subtype of breast cancer, with luminal tumors tending to have lower prevalence than basal-like or HER2-enriched tumors.27–29 In terms of IHC expression, several cut-points have been proposed to indicate p53+ tumors, including ≥1, 5, 10, or 50%, with reported frequencies ranging from 9 to 54%.32–38 In the current study, we used a threshold of ≥1% and observed 53% of the tumors to be p53+, which is similar to the 54% that was reported by van der Kooy and colleagues33 when considering any degree of nuclear staining (i.e., ≥1%).