highly significantP =2 × 10 −3
A statistical comparison of categorical data for staining intensity for normal breast, DCIS and IBC and a similar analysis of categorical data for area stained for normal breast, DCIS and IBC showed that there is a highly significant decrease in the percentage of nuclei stained for PRH ( P =2 × 10 −3 ) and decreased nuclear staining intensity ( P =2 × 10 −4 ) in tumours compared with normal breast tissue and a trend towards increased cytoplasmic staining.