In a study by Denkert and colleagues [35], pCR ratio observed in patients with Ki67 < 15% was 3.4%, while patients having Ki67 of 15-35% and > 35% had pCR ratio of 8.2% and 18.5%, respectively, in patients with HR+, HER2− BC (p < 0.0005). Here, ERBB2 is linked to breast cancer.