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Here we present a study which investigates whether ddPCR can be used to assess HER2 transcript levels in formalin - fixed paraffin embedded ( FFPE ) human breast tumors and whether these ddPCR measurements agree with prior assessments of these same samples by pathologists using immunohistochemistry ( IHC ) and in some cases fluorescence in situ hybridization ( FISH ) .
 Chemical: formalin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: formalin