Oncotype vs. IHC for ER/PR

KathyL624

Has anyone been able to find out about the differences between how oncotype measures your ER/PR vs. the path report?  According to my surgical path report, I had strong staining for ER in 99% of cells and strong staining for PR in 95% of cells.  Onctoype ER score was 9.1 (I forget the PR score).  9.1 is not even close to the top range for ER, so what does that mean?  Everyone tells me hormonal therapy is my best weapon because I was strongly hormone positive, but the oncotype numbers make me wonder.  If it matters to anyone, my overall oncotype was a 9, so I did not do chemo, per my doctors' suggestion.

letsgogolf

I understand your confusion. My ER was 100% and PR was 99.89 on original pathology. On the Oncotype report my ER was 11.7 and PR was 8.8. Neither were at the highest end of the Oncotype range. Looks like both of us have a low chance of recurrence which is good. Grade 1 is also encouraging, or so I have been told.

SpecialK

It is important to remember that when the pathologist looks at the slide he/she is looking at an extremely small area of your tumor - and tumors are not homogenous. Most pathologists are looking at 100 cells, from a random area, to get a hormonal receptor percentage - i.e., 99 out of your 100 cells stained for ER receptors, thus 99%. If the pathologist had looked at a different area of your tumor that percentage may have been different. The Oncotype tumor material is prepared differently, it is ground and run through their testing process so it may be a more average number of ER receptors, potentially representing a larger amount of tissue.

KathyL624

Even surgical pathology only looks at a small sample? So how do we truly know our percentages?

I'm confused and having less faith in all this! I know I had a low oncotype but if I was not actually highly ER positive shouldn't chemo have been more beneficial

BarredOwl

Hi SpecialK:

Oncotype uses quantitative Reverse Transcription/Polymerase Chain Reaction (qRT-PCR) to measure mRNA levels, not the actual estrogen or progesterone receptor proteins.

As you may recall from biology class: DNA is transcribed into mRNA which directs the synthesis of Protein.

IHC detects ER and PR proteins using antibody-based methods to tag or "stain" the receptor protein so it is visible.

Oncotype detects the mRNAs that encode the receptor protein.

IHC is generally considered to be the more sensitive method. In the typical case, IHC is used to determine ER and PR status for the purpose of endocrine therapy.

BarredOwl

farmerlucy

I considered getting a second opinion on the grade at Johns Hopkins. Just as I was about to do it I remembered my DH, who worked for a large medical lab, telling me that many pathologists really like to talk to patients. So about three years in, as I was still obsessing about in congruencies (is that really two words, spell checker?), I called up the pathology dept at my hospital and asked to speak with a pathologist. It turns out I was able to talk to the chief of staff, who was quite willing to pull my slides and do his own assessment.

As time has gone on I now know what I was really looking for as I did research, asked for copies of old reports, questioned every expert I could. I wanted someone to tell me it would all be ok and it wasn't coming back. I think at about my five year mark I finally accepted that there were no other answers except that "time will tell".

kira1234

Farmer unfortunately I think you're right. Time will tell