Histopathological characteristics of breast cancer and evaluation of ER alpha and Her-2neu using immunohistochemical and RT-PCR techniques

Abstract

Background and purpose: Oestrogen receptor (ER) and HER (human epidermal growth factor receptor) family signaling pathways are fundamental to guide treatment and determine prognosis. Categorizing breast cancer tumors as ER and Her-2 positive or negative is usually performed by immunohistochemistry (IHC), however the technique lacks standardization in handling tissues, staining techniques, and scoring systems. The current study aimed to compare the conventional IHC and the RT-PCR techniques in assessing the ER-alpha status in breast cancer. It also validates the application of RT-PCR technique in detecting the Her-2/neu status.
Subjects and methods: The study included 40 patients with IDC (NOS) (invasive ductal carcinoma; not otherwise specified). Breast tissue specimens were collected at the time of the elective surgery. Specimens were subjected to routine pathological examinations. ER alpha and PR receptor status; assessed by immunohistochemical staining. RNA was extracted, reverse transcribed, and amplified by PCR using ER alpha and HER-2 specific primers. Relative expression was detected by comparing the expression in normal and tumor samples relative to the housekeeping (b-actin) gene expression.
Results: IHC and RT-PCR techniques showed great discrepancies in detecting ER alpha status which might be due to the presence of ER alpha variants. RT-PCR showed higher sensitivity (72.7%) and accuracy (57.6%) than IHC in detecting ER alpha status. Gene expression of HER- 2 was detected (by RT-PCR) in 67.5% (27/40) with overexpression in 25% (10/40) of the cases.
Conclusion: IHC and RT-PCR must be combined for more informative results regarding the ER alpha and HER-2 status. Further studies are mandatory to evaluate the efficacy of anti-estrogens on ER alpha variant expression. 

KEYWORDS Human epidermal growth factor receptor (HER); Immunohistochemistry (IHC); Invasive ductal carcinoma; Not otherwise specified (IDC NOS); Estrogen receptor (ER)