# Evaluation of Grading Estrogen Receptors in Breast Cancer Using Fully Automated Rapid Immunohistochemistry Based on Alternating-Current Electric Field Technology

## TL;DR

A new automated system for breast cancer estrogen receptor staining shows high accuracy and significantly reduces processing time compared to traditional methods.

## Contribution

A fully automated rapid immunohistochemistry stainer (R-Auto) was developed and validated for estrogen receptor staining in breast cancer.

## Key findings

- R-Auto showed substantial agreement with conventional IHC (95.7% agreement rate, AC1 0.9490).
- R-Auto also demonstrated strong agreement with a commercial autostainer (92.6% agreement rate, AC1 0.9095).
- R-Auto reduced staining time from 209 minutes to 42 minutes.

## Abstract

We previously developed a rapid immunohistochemistry (R-IHC) method based on alternating-current electric field technology and have now developed a fully automated rapid IHC stainer (R-Auto). We evaluated 188 breast cancer surgical specimens at our hospital via estrogen receptor (ER) staining using R-Auto, conventional IHC, and a commercial autostainer. The specimens were scored using Allred scores, after which the staining results were compared between R-Auto and conventional IHC or the commercial autostainer. The AC1 statistic for comparison between R-Auto and conventional IHC and R-Auto was 0.9490, with a 95.7% agreement rate, and that for comparison between R-Auto and the commercial autostainer was 0.9095, with a 92.6% agreement rate. There was substantial agreement between R-Auto and each procedure. Furthermore, R-Auto shortened the time required for IHC from 210 min with the commercial autostainer and 209 min with conventional IHC to 42 min.

Background: Immunohistochemistry (IHC) is crucial for determining cancer treatments. We previously developed a rapid IHC method and have now developed a fully automated rapid IHC stainer (R-Auto). This study aimed to evaluate the clinical reliability of the R-Auto protocol for staining estrogen receptors (ERs) in breast cancer specimens and evaluate the staining performance. Methods: Between January 2015 and June 2020, 188 surgical specimens collected from breast cancer patients treated at our hospital were evaluated via ER staining using R-Auto, conventional manual IHC, and a commercial autostainer. The specimens were scored using Allred scores, after which the staining results were compared between R-Auto and conventional IHC or the commercial autostainer. Weighted kappa coefficients and AC1 statistics were used to assess the agreement between the methods. Results: The AC1 statistic for comparison between R-Auto and conventional IHC was 0.9490 (0.9139–0.9841), with a 95.7% agreement rate, and that for comparison between R-Auto and the commercial autostainer was 0.9095 (0.8620–0.9570), with a 92.6% agreement. There was, thus, substantial agreement between R-Auto and both conventional IHC and the commercial autostainer. However, R-Auto shortened the time required for IHC from 209 min with conventional IHC to 121 min. Conclusions: R-Auto enables a good staining performance in a shorter time with less effort.