MKI67 and breast cancer: The ongoing WSG-ADAPT cycle study, a prospective, randomized phase 3 trial, investigates whether patients with HR + HER2-negative early-stage breast cancer with intermediate risk based on the RS result and response to preoperative ET (i.e., RS result ≤ 25 and Ki-67 > 10% post-induction, RS result > 25 and Ki-67 ≤ 10% post-induction in c/pN0-1 patients, or RS result ≤ 25 and Ki-67 ≤ 10% in c/pN2-3 patients) obtain additional benefit from 2 years of ribociclib (a CDK4/6 inhibitor) combined with ET compared to CT followed by ET.