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CAP Breast Biomarker Reporting Template Update

 
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The College of American Pathologists (CAP) released a new version of its Breast Biomarker Reporting template (v1.6.0.0, released March 2025). It includes separate fields for IHC 0 with membrane staining that is incomplete and is faint/barely perceptible and in ≤10% of tumor cells and IHC 0 without membrane staining.1 Utilization of this updated CAP template may improve consistency of reporting HER2 IHC results for breast cancer cases with low levels of HER2 expression. These results are important for informing clinical decision making.

CAP Template for Reporting Results of Biomarker Testing of Specimens from Patients with Carcinoma of the Breast1

Pay close attention to IHC 0 cases and begin incorporating the latest CAP reporting template to improve diagnostic accuracy

View the latest CAP reporting template

HER2 IHC testing and reporting in breast cancer is a routine practice that categorizes tumors by their HER2 expression.2 Historically, only HER2-positive and HER2-negative results impacted treatment decisions.2,3 However, with the emergence of HER2-low (IHC 1+, IHC 2+/ISH-) breast cancer, reporting practices started to change.2,4 Today, reporting any level of staining, including IHC 0 with faint, incomplete staining, may be clinically relevant.2-4

HER2 Spectrum Wheel

Within the HER2 spectrum, our interpretation of IHC 0 is evolving3,4

Reporting of breast cancer tumors scored as IHC 0 with faint, incomplete staining may impact clinical decision making. As emphasis on providing discrete HER2 IHC scores in pathology reports increases, it is critical to accurately describe HER2 IHC 0 tumors.2,5

For more guidance on scoring IHC at the low end of the HER2 spectrum, view the resources below.

CAP, College of American Pathologists; HER2, human epidermal growth factor receptor 2; IHC, immunohistochemistry; ISH, in situ hybridization.

1. CAP. Reporting Template for Reporting Results of Biomarker Testing of Specimens from Patients With Carcinoma of the Breast. Version: 1.6.0.0. 2. Wolff AC, et al. Arch Pathol Lab Med 2023;147:993-1000. 3. Bardia A, Viale G. Target Oncol 2023;18(3):313-319. 4. Tarantino P, et al. Ann Oncol 2023;34(8):645-659. 5. Venetis K, et al. Front Mol Biosci 2022;9:834651.

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