DETECTION AND QUANTITATION OF HER-2 NEU GENE AMPLIFICATION IN HUMAN BREAST-CANCER ARCHIVAL MATERIAL USING FLUORESCENCE IN-SITU HYBRIDIZATION/

Amplification and overexpression of the HER-2/neu gene occurs in 25-30 % of human breast cancers, This genetic alteration is associated with a poor clinical prognosis in women with either node negative or node p ositive breast cancers, The initial studies testing this association w ere somewhat controversial and this controversy was due in large part to significant heterogeneity in both the methods and/or reagents used in testing archival material for the presence of the alteration, These methods included a number of solid matrix blotting techniques for DNA , RNA and protein as well as immunohistochemistry, Fluorescence in sit u hybridization (FISH) represents the newest methodologic approach for testing for this genetic alteration, In this study, FISH is compared to Southern, Northern and Western blot analyses as well as immunohisto chemistry in a large cohort of archival human breast cancer specimens, FISH was found to be superior to all other methodologies tested in as sessing formalin fixed, paraffin embedded material for HER-2/neu ampli fication, The results from this study also confirm that overexpression of HER-2/neu rarely occurs in the absence of gene amplification in br east cancer (approximately 3% of cases), This method of analysis is ra pid, reproducible and extremely reliable in detecting presence of HER- 2/neu gene amplification and should have clinical utility.