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PgR
- Immunohistochemistry (IHC)
Progesterone Receptor (PR) belongs to a superfamily of nuclear hormone receptors. Estrogen Receptor (ER) induces PR expression, therefore, PR status serves as an indicator of an intact ER pathway. There are two known isoforms of PR; PRα and PRβ. The current assays in clinical breast cancer measure both isoforms. PR is expressed in about 60-70% of invasive breast cancers. It is a weak prognostic factor by itself but a modest predictive factor that adds to the predictive value of ER for response to endocrine therapies, both in adjuvant and metastatic settings. The primary indication to assess PR in breast cancer is to predict response to hormonal therapies, such as tamoxifen, other selective estrogen receptor modulators (SERMs) and aromatase inhibitors.
Specimen Requirements
A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type or one (1) unbaked, unstained slide for H&E staining (required) and two to three (2-3) positively charged unstained slides (all cut at 4-5 microns) for each test/antibody ordered.
Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
Storage and Transportation
Use cold pack for transport, making sure cold pack is not in direct contact with specimen. NYS clients please provide date and time of Collection.
CPT Code(s)*
88342 x 1 or 88341 x 1 (qualitative IHC) or 88360 (quantitative/semi-quantitative – manual) or 88361 x 1 (quantitative/semi-quantitative – computer assisted)
*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.
Last Updated: August 12, 2025