Determining HER-2/Neu (H2N) Status on Needle Core Biopsies (NCBs) in the Neoadjuvant Setting: Does Florescence In-Situ Hybridization (FISH) Remain the Gold Standard for 2+ Cases in These Smaller Samples?
T D'Alfonso, Y-F Liu, S Monni, PP Rosen, SJ Shin. Weill Cornell Medical College, NY, NY
Background: Emerging data show that patients with operable, H2N overexpressed/amplified breast carcinomas have significantly better responses (more frequently obtaining pathologic complete response and longer disease-free survival) when treated with trastuzumab simultaneously with neoadjuvant chemotherapy than with chemotherapy alone. With the increasing use of neoadjuvant therapies, clinicians require information on biomarkers including H2N status at the time of NCB. Currently cases staining 2+ by immunohistochemistry (IHC) are reflexed to FISH. Although many studies have shown excellent concordance between H2N status determined by IHC versus FISH in excised tumors, the question of whether FISH determined H2N status on NCBs in 2+ staining cases is equally reliable. The purpose of this study was to determine the accuracy of FISH determined H2N status on NCB material in 2+ cases by comparing with that assessed on subsequent EXBX from the same patient's tumor.
Design: 99 patients whose NCBs and subsequent EXBXs were pathologically evaluated at our institution were identified. For each patient, unstained sections from both specimens were prepared and used for IHC or FISH. IHC was performed using the HercepTest kit (Dako, Carpinteria, CA). Parallel unstained slides were used to perform FISH (dual probe, Vysis). Statistical analyses were performed on the resulting data.
Results: 14 of 99 (14%) cases demonstrated 2+ IHC staining in the NCB specimen. 8 of 14 (57%) were not amplified in both the NCB and EXBX whereas 3 of 14 (21%) were amplified in both specimens. The remaining 3 had discordant results (1 was amplified in the NCB but not amplified in the EXBX while 2 were not amplified in the NCB but amplified in the EXBX).
Conclusions: 78% of 2+ IHC staining NCB cases demonstrated concordant FISH results in the NCB and EXBX specimens. Performing FISH on NCB material in 2+ IHC cases yields a result that is tantamount to that done by FISH on the EXBX in the majority of cases.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 10, Tuesday Afternoon