ERBB2 and breast cancer: However, Bai et al., in a meta-analysis including five cohort/case–control and 18 case-only studies, found that increased MD is more strongly linked to HER2+ cancers compared to other BC subtypes (relative risk ratios for BI-RADS 4 versus 1 of 2.58 (95% CI 1.63–4.08), when compared HER2+ over TN tumors for case only studies) [15].