ERBB2 and breast cancer: Triple-negative breast cancer (TNBC), which is estrogen receptor-negative, progesterone receptor-negative, and human epidermal growth factor receptor 2 (HER2)-negative, accounts for 15% to 20% of BC cases.[6] TNBC is associated with young age, advanced stage, and worse long-term survival compared to other subtypes.[7–9] Thike et al[10] analyzed 653 patients with TNBC and found worse disease-free survival and overall survival (OS) in young patients with TNBC compared to older patients with TNBC.