In both the current real-world analysis, and the translational program of the Plan-B study (2274 patients with HR + HER2-negative pN0-1 early-stage breast cancer), close to a tenth of patients with low risk of recurrence according to Ki-67 level were reclassified as high risk according to the RS result (9% and 8%, respectively) [29]. This evidence concerns the gene MKI67 and breast carcinoma.