ER Positivity Percentages

Last Modified: March 2, 2007

Question

Dear OncoLink "Ask The Experts,"

How do you determine if an ER or PR receptor is positive or negative when the results are reported as a percentage? I have seen 15% considered negative in some of the research, but positive in others. Is there a set definition for receptor positivity?

Answer

Kevin R. Fox, MD, Assistant Director, Clinical Affairs and Associate Professor of Hematology/Oncology at the Abramson Cancer Center of the University of Pennsylvania, responds:

In general, we consider any percentage level of receptor positivity to be "positive." However, the general accepted cutoff is 10% or higher. Reference is Goldhirsch et al. Meeting Highlights: International Expert Consensus on the Primary Therapy of Early Breast Cancer 2005, Annals of Oncology, September 2005.

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