AI and LI values within ER- DCIS did not differ between xenografts exposed to 17beta-estradiol or AE treatment compared with the controls or pretreatment values (mean AI and LI in estradiol-treated, antiestrogen-treated, and control groups 1.04% versus 0.98% versus 1.29% and 17.2% versus 20.5% versus 17.7% respectively).