ERBB2 and breast cancer: Our results are consistent with those of a recent study by Arvold et al that found a LRR rate of 0.8% in patients with luminal A breast cancer approximated as hormone receptor (HR)-positive, HER2-negative, grade 1–2 after BCT compared to 2.3% in luminal B (HR+, HER2−, grade 3), 1.1% in HER2+ luminal B (HR+, HER2+), 10.8% in HER2-enriched (HR−, HER2+) and 6.7% in basal (HR−, HER2−) cancers [8].