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Feb 10, 2018 12:25PM
Feb 10, 2018 02:12PM
Whether you were considered ER+ or ER- or "ER negative-like" would not affect advice re chemotherapy in your situation.
However, being 10% ER+ by IHC (immunohistochemistry) would ordinarily be considered ER+ for purposes of endocrine therapy, under guidelines from ASCO (which use a 1% cut-off).
The single-gene ER score in the Oncotype report does not typically override the pathologic determination of ER positive status by IHC (although there might be appropriate exceptions). This is because antibody-based IHC methods are considered to be more sensitive.
If you did not receive a recommendation for endocrine therapy, please consider seeking a second opinion, (especially as your single-gene ER score was quite near the ER Score positive/negative cut-off of 6.5 units).
General Information - Different Methodologies - Different Sensitivity
The single-gene Oncotype "scores" for ER and PR cannot be directly compared with the results of IHC, and do not necessarily override ER and PR status as determined by IHC.
Validated pathology methods ("IHC") for determining ER and PR status use antibody-based methods to detect ER protein and PR protein. The pathologist looks at whole cells. Results are reported as percent positive cells in a field of view (i.e., some cells are stained by a "molecular tag" and are seen as "positive for staining," and some cells are not stained). The percentage of cells that do stain is reported.
Oncotype uses a completely different method (Quantitative Reverse Transcriptase - Polymerase Chain Reaction, "qRT-PCR") to measure ER and PR mRNA from ground-up cells (obtained by microdissection I believe). It gives a numerical score in "units", where particular unit values falling below a specified positive/negative cut-off of X units are considered "negative" by Oncotype (if the arrow/triangle falls in the orange range at left).
Thus, IHC and Oncotype use completely different analytical methods and sample cells in a different way. They measure different molecules: ER protein versus mRNA. The numerical outputs are reported in different "units" and cannot be directly compared: percent positive cells versus score in unit values.
These methodological differences can lead to apparently differing degrees of positivity, which "confuses clinicians and unnecessarily creates doubt about validated immunohistochemistry assays:"
Krauss (2012): https://www.nature.com/articles/modpathol2011219
Best wishes as you move forward with treatment.
Stage IA IDC, 9/2013 BMX. Right: IDC (1.5 mm, grade 2) with DCIS (5+ cm), 0/4 nodes, pN0. Left: DCIS (5+ cm), 0/1 node, pN0(i+).