The basal level of the RAD51 foci score in untreated FFPE tumor samples has been previously advocated as a marker of functional HR and shown to predict olaparib response in breast cancer PDXs (Castroviejo-Bermejo et al., 2018; Cruz et al., 2018) and, more recently, to predict response to platinum-based neoadjuvant therapy in a retrospective study (Llop-Guevara et al., 2021). This evidence concerns the gene RAD51 and breast cancer.