Suggested Citation: Balko, J., I. Mayer, M. Levy, C. Arteaga. 2015. PR (PGR).
My Cancer Genome https://www.padiracinnovation.org/content/disease/breast-cancer/pgr/?tab=0
(Updated December 7).
Last Updated: December 7, 2015
PR (PGR) in Breast Cancer
Progesterone receptor (PR) protein expression occurs in 55–58% of breast cancers (Nadji et al. 2005;
Rhodes et al. 2000).
PR (PGR) mutations are not known to be important in breast cancer.
NOTE: ER = estrogen receptor
; PR =
Testing for PR Expression in Breast Cancer
Because ER and PR expression is predictive
for response with endocrine therapy and prognostic for survival outcomes, accurate
immunohistochemistry (IHC) measurements for ER and PR expression
in breast cancer are important (Hammond et al. 2010a).
Several different methods have been used to measure PR status. Per National Comprehensive Cancer
Network (NCCN) guidelines, PR expression in invasive breast cancer or ductal carcinoma
in situ (DCIS) tumor tissue should be measured with validated IHC assays (Allred et al. 2009
The ASCO/CAP guideline recommendations for ER and PR testing by IHC in breast cancer patients
specify the following algorithm for optimal ER/PR testing (Hammond et al. 2010a
Hammond et al. 2010b
1. Positive for ER or PR if finding of ≥ 1% of tumor cell nuclei are immunoreactive.
2. Negative for ER or PR if finding of < 1% of tumor cell nuclei are immunoreactive in the
presence of evidence that the sample can express ER or PR (positive intrinsic controls are
3. Uninterpretable for ER or PR if finding that no tumor nuclei are immunoreactive and that
internal epithelial elements present in the sample or separately submitted from the same
sample lack any nuclear staining.
Suggested Citation: Balko, J., I. Mayer, M. Levy, C. Arteaga. 2013. PR (PGR) in
Breast Cancer. My Cancer Genome https://www.padiracinnovation.org/content/disease/breast-cancer/pgr/
(Updated October 11).
Last Updated: October 11, 2013
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