Antonio C. Wolff, MD
The guidelines for establishing HER2 status for patients with breast cancer with unclear results on initial testing have been fine-tuned in an update that the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) recently issued.
Some Recommendations Changed
The panel has changed a recommendation regarding repeat HER2 testing of a surgical specimen. If the initial core biopsy is negative, a repeat test on the excision specimen is now optional rather than mandatory. Hammond said that clinical evidence shows the result is unlikely to change with a second test and may result in misdiagnosis.
“If you do a lot of repeat testing on the same sample, statistically what you do is increase the [odds] that you will have the wrong answer just by chance,” she said. “Repeat testing, in and of itself, is not a good idea.
Table 1. Clinical Questions Addressed in Updated HER2 Guidelines2
The panel also recommends that the same institution should perform the concomitant review to ensure “parallel interpretation and quality of the 2 assays.” Wolff said that very few group 2 specimens will be IHC 3+ and so will not be confirmed as HER2 positive. Most group 4 specimens will be confirmed HER2 negative without the need for additional testing using alternative probes, he added.
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