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Detects the estrogen receptor, a nuclear hormone receptor expressed in approximately 85% of invasive breast cancers. It serves as a strong predictive marker for response to endocrine therapies such as tamoxifen and aromatase inhibitors and is used to guide hormonal treatment decisions. Even moderate to strong staining in as little as 1% of tumor cells correlates with improved disease-free survival.
Tissue Block: Formalin-fixed, paraffin-embedded (FFPE) tumor block preferred.
Unstained Slides: Recommended 2 charged slides per stain requested (minimum of 1 slide per stain), baked or unbaked.
Fixation: Tissue must be fixed in 10% neutral buffered formalin for 6–72 hours.
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.