Interval cancers were more often HER2-positive (19.6% vs. 12.0%) with higher Ki-67 indices than screening-detected cancers (60.1% vs. 40.1%), and patients with interval cancers were more frequently node-positive (45.5% vs. 23.4%) and had more distant metastases than patients with screening-detected cancers (18.6% vs. 5.3%). This evidence concerns the gene MKI67 and cancer.