Friday, May 28, 2010 (Last Updated: 06/01/2010)
FRIDAY, May 28 (HealthDay News) -- Screening breast core needle biopsies (CNB) for human epidermal growth factor receptor 2 (HER2) using immunohistochemistry (IHC) is reliable when applying new American Society of Clinical Oncology-College of American Pathologists (ASCO-CAP) testing criteria, according to research published online May 24 in the Journal of Clinical Oncology.
Annette Lebeau, M.D., of the University Medical Center Hamburg-Eppendorf in Germany, and colleagues evaluated 500 breast cancer CNBs and the corresponding surgical specimens using IHC, and determined the results according to U.S. Food and Drug Administration-approved scoring criteria and recently published ASCO-CAP guidelines. Fluorescent in situ hybridization (FISH) testing was used to confirm HER2 status if IHC revealed score 2+ or 3+.
Using the FDA scoring criteria, the researchers found that 12.5 percent of the CNBs scored 3+ tested false-positive by IHC, while 6.1 percent tested false-positive by IHC using the ASCO-CAP guidelines. The highest probability of obtaining an accurate result was with testing both CNBs and surgical specimens by IHC (99.8 percent), while the second highest probability was using IHC on CNBs scored according to the ASCO-CAP criteria (99.4 percent).
"In conclusion, we have shown that the strategy to screen all cases of primarily diagnosed breast cancer with IHC, evaluate according to the ASCO-CAP criteria and retest only scores 2+ by FISH can be applied on CNBs. Nevertheless, quality assurance is a need that has to comprise not only analytic but also preanalytic process steps," the authors write.
Several authors disclosed financial relationships with the pharmaceutical industry.
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