It came right up for me with google - lots of hits on "allred score breast cancer". But I can't seem to copy/paste the table. It looks at intensity AND proportion of ERPR. If you scroll down a ways in this article, there's an explanation, and a table (old article but the Allred Score hasn't changed).
http://www.breastcancerupdate.com/bcu2003/4/dixon.htm
Debbie L. (not showing up as a registered person - not sure why not)