Table 2.
Inter-reader agreement for central pathologists with HER2-low training
| HER2 IHC score cutoff | OPA, % (95% CI) | Fleiss’ kappa | ||
|---|---|---|---|---|
| Pathologists 1 vs. 2 |
Pathologists 2 vs. 3 |
Pathologists 1 vs. 3 |
||
| 0 absent membrane staininga, b vs. 0 with membrane staininga 1+, 2+, 3+ | 96 (93–97) | 96 (94–98) | 97 (95–99) | 0.68 |
| 0c vs. 1+, 2+, 3+ | 94 (92–96) | 94 (92–96) | 91 (88–94) | 0.79 |
| 0, 1 + vs. 2+, 3+ | 85 (81–88) | 85 (81–88) | 94 (90–95) | 0.74 |
| 0, 1+, 2 + vs. 3+ | 97 (95–98) | 87 (84–90) | 87 (84–90) | 0.67 |
CI: confidence interval; HER2: human epidermal growth factor receptor 2; IHC: immunohistochemistry; OPA: overall percent agreement
a “IHC 0 absent membrane staining” and “IHC 0 with membrane staining” are part of the IHC 0 score per American Society of Clinical Oncology/College of American Pathologists 2018 guidelines [2]
b Cutoff explored in DESTINY-Breast06 [17]
c Cutoff for HER2-low used in DESTINY-Breast04 [12]