ESR1 and invasive ductal breast carcinoma: On the other hand, in the BRCA invasive ductal carcinoma dataset, SFRP1 expression was negatively correlated with ESR1 (rho = −0.45; p-value = 2.6 × 10−82), PGR (rho = −0.13; p-value = 4.1 × 10−6), and HER2 (rho = −0.29; p-value = 4.0 × 10−25) expression, while it was positively correlated with ESR2 (rho = 0.47; p-value = 5.7 × 10−67; Figure 1D).