In my case there was a dramatic difference between post-surgery pathology (grade 3, LVI, high ki67%) and Oncotype (low).

As for relying on lab technicians, well, one lab had me as HER2+, one had me as HER2 equivocal and one retested and got a negative- actually 4 different hospitals' labs.

If I had stayed with the first hospital I would have had chemo and been treated for HER2.

I asked for retests at three different oncology offices, and the tumor board also refused. The fourth doctor retested HER2 using 60 cells instead of 20. Ductal cells were positive but HER2- dominated so no Herceptin.

That 4th doctor also retested Oncotype and told me I could choose chemo if I wanted to. It was up to me. All the other oncos, two at major world class hospitals, relied entirely on the Oncotype.