Among ER+ patients, PELP1 tumor levels were positively correlated with tumor tissue E1 and E2 concentrations (r = 0.562, P = 0.003 and r = 0.411, P = 0.037, respectively), E1 and E2 in normal tissue (r = 0.461, P = 0.018 and r = 0.427, P = 0.030, respectively) and E1, E2 and E1S plasma levels (r = 0.576, P = 0.003; r = 0.456, P = 0.025 and r = 0.406, P = 0.049, respectively). This evidence concerns the gene ESR1 and neoplasm.