ERBB2 and breast cancer: For example, low BMI (<18.5 kg/m2, OR [95% CIs]: 2.43 [1.22–4.87]), postmenopausal status (0.77 [0.61–0.96]) and history of abortion (1.35 [1.05–1.75]) were independently associated with HER2‐zero BC, while OC (1.40 [1.14–1.72]) and HRT (1.46 [1.06–2.03]) were independently associated with HER2‐low BC (Figure 2C and Table S5).