HScore as a diagnostic tool in ERBB2 equivocal (immunohistochemistry 2+) breast cancer.

Abstract

Introduction: ERBB2 is amplified or overexpressed in 15% to 20% of primary invasive breast cancers. Despite the aggressive nature of ERBB2-positive breast cancers, the development of anti-ERBB2 therapy has resulted in better prognoses. HScore is a scoring system that broadens immunohistochemistry (IHC) results into a quantitative range. The aim of this retrospective study was to evaluate whether the HScore can be used to predict all ERBB2 IHC-equivocal cases as positive or negative without the need for fluorescence in situ hybridization confirmation.

Methods: Image acquisition and processing tools were used on previously collected tissue slides from patients with ERBB2 IHC 2+ breast cancer from 2014 to 2023. After image acquisition, HScore values were calculated using variables from image analysis software.

Results: The mean HScore values in ERBB2-positive cases were higher (3.06) than in ERBB2-negative cases (2.62). Receiver operating characteristic curve analysis yielded an area under the curve of 0.668 (95% CI, 0.523-0.812), indicating poor predictive accuracy. The optimal HScore cutoff of 2.6007 provided moderate sensitivity (0.77) but limited specificity (0.58).

Discussion: Although the HScore showed moderate predictive accuracy, it lacked the reliability to replace fluorescence in situ hybridization as the gold standard. Future research should focus on refining the methodology and integrating it with other diagnostic approaches to enhance accuracy and clinical utility.