ERBB2 and breast cancer: In case-case studies (Fig. 3; Supplementary Fig. 12) compared to luminal A, there was 15% lower risk of TNBC (RR: 0.85, 95% CI: 0.74, 0.99, I2 = 58.8%, p < 0.001), while luminal B breast cancer (RR: 0.90 95% CI: 0.80, 1.00) and HER2-overexpressing BC (RR: 0.92 95% CI: 0.79, 1.07) results were not significant.