Do you give Her2 targeted therapy in patients with breast cancer with Her2 testing showing FISH ratio equal or more than 2.0 but Her2 copy number less than 4.0, with further testing showing IHC 1+?

According to the latest ASCO/CAP clinical practice guidelines updated focus: HER2 testing in breast cancer published in JCO 2018, if a case has a HER2/CEP17 ratio of ≥2.0 but the average HER2 signals/cell is <4.0, IHC testing for HER2 should be performed using sections from the same tissue sample ...

I am going to take a slightly more nuanced answer to this question.

These patients (Her2:CEP17 ratio > 2 but copy number less than 4) were allowed on all of the early adjuvant trastuzumab trials (Her2, NCCTG 9831, B31, BCIRG 006) as well as the early metastatic trastuzumab trials.

However, the number ...