Tag Archives: CAP protocols/guidelines/recommendations

August 2023—Seemingly channeling the inspiration of Magritte and his famous pipe, pathologists are painting a new picture of what has long been an everyday object in their own world: HER2. To paraphrase the master: Ceci n’est pas facile. For years, HER2 testing in breast cancer has seemed self-evident, ever since the HER2-targeted therapy trastuzumab and its companion diagnostic arrived on the scene a quarter of a century ago. Pathologists became comfortable using immunohistochemistry to identify 3+ cases and turning to in situ hybridization techniques to sort through less obvious ones. But early last summer, a variant of the drug, trastuzumab-deruxtecan (T-DXd), shook up that routine. When researchers presented results from the Destiny-Breast04 study at the 2022 ASCO annual meeting, showing that T-DXd significantly improves survival in so-called HER2-low metastatic breast cancer, attendees responded with a minutes-long standing ovation. They then returned from the meeting like evangelicals from the revival tent.

April 2023—Molecular testing guidelines say that the neoplastic cell content of each specimen should be assessed, but there are no formal recommendations or guidelines on how to do the assessment.