Multimodal molecular profiling of invasive ductal carcinoma: High concordance of qPCR with FISH in HER2 assessment and exomic landscape of high-risk subtypes.
qPCR resolved definitive HER2 amplification in 41.3% of equivocal immunohistochemistry 2+ breast cancer cases
Multimodal molecular profiling of invasive ductal carcinoma: High concordance of qPCR with FISH in HER2 assessment and exomic landscape of high-risk subtypes.
Accurate evaluation of HER2 status is critical for the targeted management of invasive ductal carcinoma (invasive ductal carcinoma) of the breast; however, resolving equivocal immunohistochemistry (immunohistochemistry) results remains a significant clinical challenge.
This study aims to comparatively evaluate immunohistochemistry, fluorescence in situ hybridization (FISH), and quantitative polymerase chain reaction (qPCR) for precise HER2 assessment, while mapping the broader genetic landscape of aggressive invasive ductal carcinoma subtypes using whole-exome sequencing (whole-exome sequencing).
We comprehensively analyzed 160 histopathologically confirmed invasive ductal carcinoma samples using immunohistochemistry, FISH, and qPCR to evaluate hormone receptor and HER2 amplification status.
qPCR demonstrated a high diagnostic concordance with gold-standard FISH for detecting HER2 gene amplification across all ASCO/CAP classification groups (sensitivity 96.4%, κ = 0.94; p < 0.05).
Furthermore, exploratory genomic profiling via whole-exome sequencing revealed profound intratumoral heterogeneity: triple-negative breast cancer samples frequently harbored pathogenic variants in TP53, BRCA1, and MYCN, whereas the HER2 3 + cohort exhibited prominent mutations in PAK1, CUL3, and TP53.
Our findings establish qPCR as a highly robust and accurate diagnostic adjunct for resolving clinically equivocal HER2 cases in invasive ductal carcinoma.
Furthermore, while restricted to a limited exploratory subset, the integration of targeted genomic profiling identified complex mutational hubs driving aggressive breast cancer phenotypes.
These hypothesis-generating insights provide a vital framework for bridging accurate diagnostic stratification with future precision oncology strategies.