Furthermore, RT improved RR and DFS in luminal A (aHR = 0.15, p = 0.0004 and 0.29, p < 0.0001), luminal B/HER2-negative (aHR = 0.06, p = 0.0093 and 0.46, p = 0.028), and luminal B/HER2-positive breast cancers (aHR = 0.14, p = 0.01 and 0.38, p < 0.0001), respectively. Here, ERBB2 is linked to breast cancer.