VOLUME 19 NUMBER 1 (January to June 2026)

IHC/FISH concordance and prognostic value of microarray-based genomic profiling tests in breast cancer molecular subtyping: A systematic review

Breast cancer is a major public health concern worldwide. Accurate molecular subtyping is essential for appropriate patient management. Conventional pathology-based (immunohistochemistry/fluorescence in situ hybridization, IHC/FISH) tests have been the cornerstone of molecular subtyping, but newer genomic-based microarray techniques have shown promise to better classify tumors. Therefore, we aimed to systematically review the concordance and prognostic value of microarray-based breast cancer subtyping techniques. Scopus, Google Scholar, PubMed and Cochrane databases were systematically searched according to PRISMA guidelines. Articles comparing IHC/FISH- and microarray-based subtyping were included. Data on concordance, treatment response, and survival outcomes were extracted and analyzed. Independent reviewers assessed all articles against the inclusion and exclusion criteria. The concordance of microarray with IHC/FISH varied in the selected 45 articles. Studies using TargetPrint reported up to 100% concordance while one PAM50 study reported concordance rates as low as 54–60%. Some BluePrint-based microarray assays reclassified approximately 18% of luminal tumor to basal type, and 5% of ER+HER2- tumors to basal type. Microarray-based technologies have shown potential in prognosticating treatment outcomes and survival, and they may enhance breast cancer subtyping and improve the prediction of clinical outcomes. Future directions should focus on the standardization of microarray-based subtyping techniques and validating their clinical utility in various populations.