Test is available with or without interpretation.
Interpretation: Semi-Quantitative Immunohistochemistry, Manual
Estrogen and Progesterone Receptor Scoring System and Criteria
-Progesterone Positive- Nuclear staining of 1% or more of the tumor cells
-Estrogen Positive- Nuclear staining greater than 10% tumor cells
-Estrogen Low Positive- Nuclear staining 1-10% of tumor cells with any staining
-Negative- Nuclear staining of less than 1% of tumor cells
-Indeterminate- Specimen is considered indeterminate as result of type of fixative used (non-10% neutral buffered formalin), time to fixation (>1 hr), duration of fixation (<6 hr or >72 hr), strong decalcification, or inappropriate staining of normal internal or external assay control. Alternative samples for retesting is recommended.
Note: Tumor is evaluated in the context of internal and external control reactivity and of pre-analytical and analytical variables.
-Percent of positive-staining tumor cell nuclei is determined by estimation and reported as either 1-10%, 11-50% or >50%.
-Staining Intensity- Weak, moderate, or strong staining intensity is based on an estimate of the average staining intensity of positively stained tumor cells over the entire tumor present in the tissue section relative to positive and internal (benign glands) controls.
For Estrogen Receptor Low Positive Results- The cancer in this sample has a low level (1-10%) of Estrogen Receptor expression by IHC. There are limited data on the overall benefit of endocrine therapies for patients with low level (1-10%) Estrogen Receptor expression, but they currently suggest possible benefit, so patients are considered eligible for endocrine treatment. There are data that suggest invasive cancers with these results are heterogeneous in both behavior and biology and often have gene expression profiles more similar to Estrogen Receptor-negative cancers.
Estrogen Receptor is a rabbit monoclonal, clone SP1, and Progesterone is a mouse monoclonal, clone 16. Detection system used is a polymer. Test is validated on paraffin-embedded tissue fixed in 10% Neutral Buffered Formalin, and interpretation follows the American Society for Clinical Oncology (ASCO) and College of American Pathologist (CAP) guidelines.
Per ASCO/CAP guidelines, Estrogen and Progesterone IHC test results are valid for non-decalcified, paraffin-embedded specimens fixed in 10% neutral buffered formalin between 6 and 72 hours. Cold ischemic time should be no more than one hour. Results from specimens fixed outside these parameters should be interpreted accordingly.
Reference: Allison, et al., Arch Pathol Lab Med, 144:545-563, 2020.