ER/PR + %

Hi Karina,  I came across this information a while back.  It is from the College of American Pathologist's newsletter,  "CAP Today", April 2010.

On one point, everyone agrees: Current ER/PgR testing, regardless of how accurate it is, doesn’t tell the whole story. “For all practical purposes,” says Dr. Osborne, “having a correct positive ER or PgR result doesn’t guarantee that the hormonal therapy will work.”

And, says University of Michigan oncologist Daniel Hayes, MD, another co-author of the guideline, the benefit seen from hormonal therapy seems to level off at about 30 percent to 50 percent positivity. “A patient is not more likely to benefit if her tumor has 100 percent positive cells versus 50 versus 30.”

I think they are saying that not everybody who is ER+ benefits from endocrine therapy.  We all know that.  Some of us don't benefit, others benefit for a while then stop, and still others benefit greatly.  They don't know who fits into which category.  I think they are saying this...  If our BC is destined to respond to the therapy, higher levels (above 30% I guess) don't mean we benefit more or are more likely to benefit.  Now I am interpreting it that way.  Maybe I'm wrong.

Hi mmm5,  I went back to that same article and found that if only 1% of cells show moderate staining, there is benefit to endocrine therapy.  Here is what they said:

The evidence in support of the one percent cutoff comes from research by Washington University pathologist D. Craig Allred, MD, one of the guideline’s co-authors and a member of its steering committee, and colleagues (Harvey JM, et al. J Clin Oncol. 1999.17:1474–1481). Guideline co-author David Hicks, MD, says the researchers took tumors tested by IHC’s predecessor—ligand-binding assays—and performed ER testing on them using IHC. “They found that if the Allred score... was below three, the benefit from endocrine therapy appeared to be lost.” A score of three equates to either one to 10 percent of cells showing weak staining or as few as one percent of invasive tumor cells showing moderate staining, says Dr. Hicks, professor of pathology and laboratory medicine at the University of Rochester (NY) Medical Center. This has been simplified to greater than one percent tumor cells staining for ER as an indication that the patient is a candidate for endocrine therapy. 

I'm not sure. . . but my onc did say that you are either estrogen postive or not--just like you are either pregnant or you're not.  She told me any estrogen involvement warrants anti-hormonal treatment.  I'm at about 10% and on femara.