The immunohistochemical surrogate panel (ER, PR, HER2, EGFR, and CK5/6) used to define the breast cancer subtypes has been previously published [ 2, 17].
Breast cancer intrinsic subtypes were classified according to an immunohistochemistry (IHC) surrogate panel [ 20, 21] as follows: luminal [estrogen receptor (ER) positive and/or progesterone receptor (PR) positive], HER2+ [HEregardlessless of hormone receptor status], and triple-negative [ER-, PR-, and HER2-].
Immunohistochemical surrogate panels are also proposed to potentially identify the molecular-based groups.
However, some of the immunohistochemistry surrogate panels proposed can potentially identify the molecular-based groups according to classification flowcharts [ 7] (figure 1).
Numerous studies have also shown that basal-like breast cancer can be specifically identified using IHC surrogate panels including ER, PR and HER2 negativity and either EGFR or CK5/6 positivity (ER-, PR-, HER2-, CK5/6+ and/or EGFR+) [ 8, 19, 26, 43, 44].
Therefore, some recent studies have raised the issue of using an immunohistochemical marker for assessment of proliferation (for example, Ki-67) to be used in combination with other IHC surrogate panels used for BC molecular classification: ER, PR, and HER2 [ 16, 17].
With the practical difficulties of gene-expression profiling as a routine diagnostic tool, immunohistochemical surrogate panels have been introduced to identify BLBCs that are 'triple-negative breast cancers' (TNBCs) (estrogen receptor (ER -negative, progER -negativeeprogesteronegative, HEreceptorverexPR -negative, 3].
Nonetheless, Mr. Batra came to be viewed largely as Mr. Norman's surrogate on a panel that critics contend rubber-stamped the party's favored candidates, using criteria that had more to do with campaign contributions than legal acumen.
The PAM50 gene set is often used for gene expression-based subtyping; however, surrogate subtyping using panels of immunohistochemical (IHC) markers are still widely used clinically.
By using the RNA standards as surrogate biomarkers, the panels were tested to gauge the confidence of assigning differential or non-differential expression of a biomarker at particular levels of transcript abundance or magnitude of fold change.
Ordinary Kriging and Design of Experiments (DOE) approaches are used to construct the surrogate models by approximating panel and viscous solution algorithms which are primarily used to solve the flow around airfoils and aircraft wings.
