Concordance between immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for HER2 determination and correlation with clinical and pathological data.

e11616 Background: In November 2013 the American Society of Clinical Oncology (ASCO) and the College of American Pathologists updated the guidelines for determining HER2 status in order to improve their accuracy and usefulness as a predictive marker in breast cancer (AC Wolff et al. 2013). We studied the correlation between IHC and FISH in our hospital using the previous 2007 ASCO guidelines. These data serve as a reference for comparison with the new recommendations. Methods: Patients diagnosed with HER2-positive invasive breast cancer with HER2 status determined by both IHC and FISH between January 2012 and August 2013, were retrospectively analyzed. Clinical and pathological data, response, and correlation between IHC and FISH were evaluated. Results: One-hundred and thirteen patients were included. Median age: 58 years, ECOG 0-1: 99%, hormonal status: positive 68%, metastatic disease at diagnosis: 4%. HER2 status by IHC was: negative (1+), borderline (2+) and positive (3+) in 11%, 53% and 36%, respect...