The proportion of BC subtype was significantly different by age groups: ER+ or PR+ BC and HER2− BC commonly occurred in women in the 40 to 49 years age group (70.1%), whereas ER−, PR−, and HER2− BC (ie, TNBC) commonly occurred in women younger than 40 years (21.6%) (Table 1). The gene discussed is ESR1; the disease is breast cancer.