MKI67 and ductal breast carcinoma in situ: To investigate the prognostic differences between patients with various clinical and pathological characteristics who received BCS and mastectomy, we subdivided them according to different variables (age, tumor location, clinical T stage, clinical node status, tumor subtype, tumor grade, presence of DCIS in pre-NAT biopsy, Ki-67 index, and pCR) and conducted stratified multivariate Cox proportional risk regression analysis on the effects of the surgical procedure (BCS and mastectomy) on OS (Table 3) and DFS (Table 4).