Age of paraffin embedded tissue - (Feb/23/2012 )

hi,
I wolud like to ask about acceptable age of paraffin embedded tissue for protein analysis by immunohistochemistry. How old can they be? Does immunohistochemistry work on archive material? We have some 5/6- year samples from HNSCC. We want to check occurence of gene products with altered expression.

I will be geratfull for an answer

joanna

We have done IHC on paraffin tissue as old as 9 years and had no issue.