For a HER2 positive patient who has undergone neoadjuvant HER2-directed therapy, do you offer adjuvant trastuzumab if the surgical specimen is HER2 negative?
Answer from: Medical Oncologist at Academic Institution
I still would give trastuzumab for a year. The neoadjuvant thereapy may have destroyed the Her2 positive clones in the breast, but there still could be micromets distantly that are Her2 positive.
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Answer from: Medical Oncologist at Community Practice
Conversion to HER2 negativity has been reported as high as 28% of cases."Loss of HER2 and disease prognosis after neoadjuvant treatment of HER2+ breast cancer" (Branco FP et al., Am J Transl Res 2019)