Question: What is the difference between a Her2/neu score 2+ and score 2.6?

Answer: It sounds like your cancer was first tested using immunohistochemistry (IHC) and it was scored 2+. Approximately 25-30% of cancers that are 2+ by immunohistochemistry will be amplified by FISH (fluorescence in situ hybridization). Thus, all cancers that get a score of 2+ by IHC should be evaluated by FISH which looks at the HER2 gene itself to see if it is amplified. Your report will show what is called a “ratio” and that ratio has to be greater than 2.2 to be amplified. So it looks like your cancer is HER2 amplified with a ratio of 2.6.