For instance, in patients with breast cancer who failed to achieve pathological complete response (PCR) following neoadjuvant systemic therapy (NST), a study using a 30% cutoff demonstrated that both Ki67C (percentage change in Ki67 before and after NST) and Ki67T (post-surgical Ki67 index) were independent predictors of DFS (21). This evidence concerns the gene MKI67 and breast carcinoma.