In what situation would you check receptor status (ER/PR/HER2) on more than one lesion in a multifocal breast cancer?

This is should be performed when there is a discordant response to therapy. For example, a patient with multifocal HER2 positive breast cancer has tumor progression through neoadjuvant HER2 directed therapy, it is reasonable to re-check receptor status. Another instance may be considered when one lesion in a multifocal breast cancer is HER2 equivocal by IHC, FISH, and reflex test. There are other scenarios where checking receptor status on more than one lesion would provide useful information th...

I would check if the focus is ER/PR positive and HER2 negative or second focus is higher grade then I would check . I also check the Oncotype dx in multifocal tumor if there is disparity between the size and grade between the focus. There is a 10 percentage chance for you to see difference between the tumors