Trastuzumab, tested only as a single agent, has been shown to achieve 7% response in heavily pretreated patients with AOC with 3+ and 2+ HER2 immunostaining by immunohistochemistry (IHC).

[18] Although it is not mandatory to follow the guidelines, they certainly are of utmost help to all surgical or molecular pathology laboratories that perform HER2 testing in their daily practice.

The HER2-low and HER2-ultralow breast cancer subtype designations have led to a changed landscape in HER2-directed therapies, as well as a desire for more sensitive assays that may better quantify ...

2 Approximately 70% of diagnosed cases are considered what has been historically called HR positive, HER2 negative breast cancer (measured as HER2 score of IHC 0, IHC 1+ or IHC 2+/ISH-).