ESR1 and breast cancer: In view of numerous technical limitations of the IHC based assessment, we used an established and certified RT-qPCR based assessment that is in clinical routine use for breast cancer (MammaTyper) to enable objective quantitation of mRNA expression of ESR1, PGR, ERBB2 and MKI67 in stage pT1 NMIBC with superior sensitivity and prognostic value.