Fluorescence In Situ Hybridization (Fish) Technique By Reference Centers For Her2 Status Determination In Metastatic Breast Cancer: Quality Assurance Results Of Fish 2002 Study

Abstract Abstract #2069 Background: Concordance between IHC and FISH in local and regional centers was evaluated in the FISH 2002 Study. Primary metastatic breast cancer (MBC) tumor samples were tested by IHC for HER2 status according to in-house techniques at 18 regional (n=871) and 81 peripheral (n=670) centers in France between 2002 and 2006. All samples were tested by FISH at regional centers [Penault-Llorca et al. SABCS 2006]. This second part of the study comprises quality assurance evaluation of FISH techniques.
 Methods: 464 cases were selected according to the protocol and were either re-assessed using archived pictures or retested by 3 reference centers (Clermont-Ferrand, Strasbourg, Paris-Curie). 246 samples were re-assessed and 166 were retested.
 Results:Global discordance combining re-assessment and retesting results was 10.7% in the first half of the study and 5.1% in the second part (p=0.041).
 
 Discussion: Concordance was excellent for negative (100%) and IHC 2+ cases (97%). Among low amplification cases (≥6 and <8 copies), 70% were concordant: discordant cases were mainly interpretation pitfalls of polysomic cases, emphasizing the importance of double-stained FISH analyses. These quality assurance results demonstrate that overall concordance and quality of HER2 status determined by FISH has improved significantly over time. This improvement is likely to be related to introduction of rigorous quality control procedures, training, and education, all of which should be continued. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2069.