Since two studies with untreated primary breast cancer demonstrated a PARPi response in 56–68% of TNBC patients, and four predictive biomarkers (HRDetect, baseline RAD51 foci, BRCA1ness, and 63-gene signature) predicted BRCAness in 45–69% of TNBCs, it is highly probable that PARPi can be effective as monotherapy in about ~60% of early TNBCs. Here, RAD51 is linked to breast cancer.