ESR1 and breast cancer: After sensitivity analyses were conducted, we still observed a trend of the pooled effect towards a higher AR mRNA levels in BC patients expressing either ER (Figure 3A), PgR (Figure 3B) or being ER+/PgR+ (SMD: 0.210; 95% CI: 0.096–0.323; p < 0.001) (Supplementary Figure S3).