Letrozole Is More Effective Neoadjuvant Endocrine Therapy Than Tamoxifen for ErbB-1– and/or ErbB-2–Positive, Estrogen Receptor–Positive Primary Breast Cancer: Evidence From a Phase III Randomized Trial

Abstract

ER+, ErbB-1+, and/or ErbB-2+ primary breast cancer responded well to letrozole, but responses to tamoxifen were infrequent. This suggests that ErbB-1 and ErbB-2 signaling through ER is ligand-dependent and that the growth-promoting effects of these receptor tyrosine kinases on ER+ breast cancer can be inhibited by potent estrogen deprivation therapy.