Quantitative expression of Estrogen, Progesterone and Her-2 and their correlation with Immunohistochemistry in breast cancer at Uganda Cancer Institute

Abstract

The detection of Estrogen Receptor (ER), Progesterone Receptor (PR) and Human epidermal growth factor receptor 2 (HER-2) is important in stratification of breast cancer and is a basis in selection of therapeutic modalities. This study aimed at determining the quantitative expression of ER, PR and HER-2 in relation to IHC and establishing their quantitative baseline Ct values. The study evaluated 20 samples for ER, PR and HER-2 using IHC and quantitative PCR technique. One portion of the breast tissue biopsy was fixed immediately in 10% buffered formalin and another preserved in RNAlater. After the histological confirmation of breast cancer by H&E technique, FFPE positive cases were matched with their corresponding RNAlater samples for IHC and qPCR. Following RNA extraction and quantification with a Nano drop, cDNA was synthesized, used specific primers with GAPDH as a reference gene to normalize the qPCR experiments. ER and PR had the similar IHC results with each giving 60% (n=12) of the cases being positive and 40% (n=8) negative cases. HER-2 had 70% (n=14) negatives cases, 25% (n=5) positives and 5% (n=1) equivocal case. A notable quantitative amplification of the ER, PR and HER-2 for the IHC reported triple negatives is reported. The mean Ct values for the hormonal receptors correlated with what has been previously studied with ER being 19.631, PR, 25.410 and HER-2 at 25.695. There was no significant difference between the mean Ct values of RNAlater and FFPE with their P-values being 0.9919, 0.0896 and < 0.0001 for ER, PR and HER-2 respectively. P-values; 0.9919 and 0.0896 for ER and PR respectively being greater than 0.05 it’s a borderline significance although HER-2 had a statistical significance. With a concordance in detection of these breast cancer hormonal receptors, qPCR can be used.